

InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
251. |
Find the coordinates of a point A, where AB is the diameter of circle whose center is (2, -3) and B is (1, 4). |
Answer» Let the coordinates of point A be (x, y) If AB is the diameter, then the center in the mid-point of the diameter So, (2, -3) = (x + 1/ 2, y + 4/ 2) 2 = x + 1/2 and -3 = y + 4/ 2 4 = x + 1 and -6 = y + 4 x = 3 and y = -10 Therefore, the coordinates of A are (3, -10) |
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252. |
The center of a circle is (2a, a – 7). Find the values of a if the circle passes through the point (11, -9) and has diameter 10√2 units. |
Answer» Given, Diameter of the circle = 10√2 units So, the radius = 5√2 units Let the center of a circle be 0(2a, a-7) and the circle passes though the point P (11, -9). Then, OP is the radius of the circle OP = 5√2 OP2 = (5√2) = 50 (11- 2a)2 + (-9 – a + 7)2 = 50 121 – 44a + 4a2 + 4 + a2 + 4a = 50 5a2 – 40a + 75 = 0 a2 – 8a + 15 = 0 (a – 5)(a – 3) = 0 [Factorisation method] So, a = 5 or a = 3 |
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253. |
In which ratio does the point (-1, -1) divides the line segment joining the pints (4, 4) and (7, 7) ? |
Answer» Suppose the point C(-1, -1) divides the line joining the points A(4, 4) and B(7, 7) in the ratio k : 1 Then, the coordinates of C are (7k+4/k+1,7k+4/k+1) But, we are given that the coordinates of the points C are (-1, -1). So, 7k+4/k+1=-1=>k=-5/8 Thus, C divides AB externally in the ratio 5 : 8. |
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254. |
In what ratio does the X-axis divide the line segment joining the points (2, -3) and (5, 6) ? |
Answer» Let the required ratio be k : 1. Then the coordinates of the point of division are (5λ+2/k+1,6λ-3/k+1). But, it is a point on X-axis on which y-coordinate of every point is zero. So, 6λ-3/k+1=0 => k=1/2 Thus, the required ratio is 1/2: 1 or 1 : 2. |
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255. |
For each of the following points, write the quadrant in which it lies.(-6, 3)(-5, -3)(11, 6)(1, -4)(-7, -4)(4, -1)(-3, 8)(3, -8) |
Answer» 1. For the coordinate (-6, 3) -6 which is the x-coordinate is negative and 3 which is the y-coordinate is positive. Therefore, (-6, 3) lies in the II quadrant. 2. For the coordinate (-5, -3) -5 which is the x-coordinate is negative and -3 which is the y-coordinate is negative. Therefore, (-5, -3) lies in the III quadrant. 3. For the coordinate (11, 6) 11 which is the x-coordinate is positive and 6 which is the y-coordinate is positive. Therefore, (11, 6) lies in I quadrant. 4. For the coordinate (1, -4) 1 which is the x-coordinate is positive and -4 which is the y-coordinate is negative. Therefore, (1, -4) lies in the IV quadrant. 5. For the coordinate (-7, -4) -7 which is the x-coordinate is negative and -4 which is the y-coordinate is negative. Therefore, (-7, -4) lies in the III quadrant. 6. For the coordinate (4, -1) 4 which is the x-coordinate is positive and -1 which is the y-coordinate is negative. Therefore, (4, -1) lies in the IV quadrant. 7. For the coordinate (-3, 8) -3 which is the x-coordinate is negative and 8 which is the y-coordinate is positive. Therefore, (-3, 8) lies in the II quadrant. 8. For the coordinate (3, -8) 3 which is the x-coordinate is positive and -8 which is the y-coordinate is negative. Therefore, (3, -8) lies in the IV quadrant. |
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256. |
Write the axis on which the given point lies.(2, 0)(0, -5)(-4, 0)(0, -1) |
Answer» 1. Since the point (2, 0) is of the form (x, 0) it lies on the x-axis. 2. Since the point (0, -5) is of the form (0, y) it lies on the y-axis. 3. Since the point (-4, 0) is of the form (x, 0) it lies on the x-axis. 4. Since the point (0, -1) is of the form (0, y) it lies on the y-axis. |
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257. |
Which of the following points lie on the x-axis?A (0, 8)B (4, 0)C (0, -3)D (-6, 0)E (2, 1)F (-2, -1)G (-1, 0)H (0, -2) |
Answer» The points which lie on the x-axis are of the form (x, 0) Therefore, the points which lie on the x-axis are B (4, 0), D (-6, 0) and G (-1, 0). |
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258. |
Write the abscissa of the each of the following points:(i) (0,5)(ii) (3,7)(iii) (-2,4)(iv) (6, -3) |
Answer» (i) Abscissa of (0,5) is 0 |
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259. |
The values of a and b for which the two circles :x2+ y2+ 2(1 –a)x + 2(1 + b)y + (2 –c) = 0 and x2+ y2+ 2(1 + a)x + 2(1 –b)y + (2 + c) = 0 cut orthogonally are? |
Answer» 2[g1g2 +f1f2] =c1 +c2 a=0 and b=0 |
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260. |
Write the ordinate of the each of the following points:(i) (4,0)(ii) (5,2)(iii) (1,-4)(iv) (-10,-7) |
Answer» (i) Ordinate of (4,0) is 0 |
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261. |
In which of the following quadrants does the point P (2,-3) lie?(a) I (b) II (c) III (d) IV |
Answer» (a) IV Explanation: We know that abscissa is positive and coordinate is negative in IV quadrant. |
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262. |
In which of the following quadrants does the point P (-7, -1) lie?(a) I (b) II (c) III (d) IV |
Answer» (c) III Explanation: We know that abscissa and coordinates are negative in III quadrant. |
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263. |
In which of the following quadrants does the point P (3, 6) lie?(a) I (b) II (c) III (d) IV |
Answer» (a) I Explanation: We know that abscissa and coordinates are positive in I quadrant. |
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264. |
The point (0, 5) lies on ………………. A) Both X and Y – axes B) Origin C) Y-axis D) X – axis |
Answer» Correct option is (C) Y-axis Point whose x-coordinate is zero lies on Y-axis. \(\therefore\) Point (0, 5) lies on Y-axis. Correct option is C) Y-axis |
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265. |
If origin is the centroid of a triangle, whose vertices are (3, 2), (-6, y) and (3,-2), then y = …………………. A) 0 B) 3 C) 2 D) 6 |
Answer» Correct option is (A) 0 Vertices of triangle are (3, 2), (-6, y) and (3,-2). \(\therefore\) Centroid of triangle \(=\left(\frac{3+(-6)+3}3,\frac{2+y+(-2)}3\right)\) \(=(0,\frac y3)\) But given that centroid of triangle is origin (0, 0). \(\therefore\) \((0,\frac y3)=(0,0)\) \(\Rightarrow\frac y3=0\) (By comparing y-coordinate) \(\Rightarrow y=0\) Correct option is A) 0 |
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266. |
What is the angle between the lines whose equations are: 3x + y – 7 = 0 and x + 2y + 9 = 0.(a) 45º (b) tan–1 \(\big(\frac{5}{2}\big)\)(c) 135º (d) tan–1 \(\big(\frac{3}{4}\big)\) |
Answer» (a) 45º 3x + y – 7 = 0 ⇒ y = –3x + 7 ⇒ Slope (m1) = –3 x + 2y + 9 = 0 ⇒ y = \(\frac{-x}{2}\) - \(\frac{9}{2}\) ⇒ Slope (m2) = \(-\frac{1}{2}\) If θ is the angle between the given lines, then tan θ = \(\big|\frac{m_1-m_2}{1+m_1m_2}\big|\) = \(\bigg|\frac{-3-\big(\frac{1}{2}\big)}{1+(-3)\big(-\frac{1}{2}\big)}\bigg|\) = \(\bigg|\frac{-\frac{5}{2}}{1+\frac{3}{2}}\bigg|\) = \(\bigg|\frac{-\frac{5}{2}}{\frac{5}{2}}\bigg|\) = 1 ∴ θ = 45°. |
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267. |
Which of the following cannot be a point on Xaxis ? A) (-2, 0) B) (0, 2) C) (2, 0) D) (4, 0) |
Answer» Correct option is (B) (0, 2) A point can lie on X-axis if its y-coordinate is zero. Since, y-coordinate of point (0, 2) is \(2\neq0.\) \(\therefore\) (0, 2) does not lie on X-axis. Correct option is B) (0, 2) |
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268. |
Find the equation of the line which passes through the point of intersection of the lines 2x – y + 5 = 0 and 5x + 3y – 4 = 0 and is perpendicular to the line x – 3y + 21 = 0. (a) 2x + y + 10 = 0 (b) 3x + y + 21 = 0 (c) 3x + y = 0 (d) 3y – x + 21 = 0 |
Answer» (c) 3\(x\) + y = 0 The equations of the two lines whose point of intersection is needed are: 2\(x\) – y = –5 ...(i) 5\(x\) + 3y = 4 ...(ii) 3 x Eqn (i) + Eqn (ii) ⇒ (6\(x\) – 3y) + (5\(x\) + 3y) = –15 + 4 ⇒ 11\(x\) = –11 ⇒ \(x\) = –1 Putting \(x\) = –1 in (i), we get –2 – y = –5 ⇒ y = 3. ∴ Point of intersection is (–1, 3). Slope of line \(x\) – 3y + 21 = 0, i.e., y = \(\frac{x}{3}\) + 7 is \(\frac{1}{3}.\) ⇒ Slope of line perpendicular to line \(x\) – 3y + 21 = 0 is –3 [∵ m1 × m2 = –1] ∴ Equation of a line through (–1, 3) with slope –3 is y – 3 = – 3 (\(x\) + 1) ⇒ y – 3 = –3\(x\) – 3 ⇒ 3\(x\) + y = 0. |
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269. |
In a locality, there is a main road along North – South direction. The map is given below. With the help of the picture answer the following questions.i) What is the 3rd object on the left side in street no. 3 while going in east direction ? ii) Find the name of the 2nd house which is on right side of street 2 while going in east direction. iii) Locate the position of Mr. K’s house. iv) How do you describe the position of the post office ? v) How do you describe the location of the hospital ? |
Answer» i) Water tank ii) Mr. J’s house iii) In street No. 2, 3rd house on right side. iv) In street No. 4, the first house on right side. v) In street No. 4, the last house on left side. |
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270. |
Which of the following is the point of intersection of X – axis and the line y = x + 5? A) (0, 5) B) (5, 0) C) (0, -5) D) (-5, 0) |
Answer» Correct option is (D) (-5, 0) y-coordinate of any point on X-axis is zero. Put y = 0 in line y = x+5, we obtain x+5 = 0 \(\Rightarrow\) x = -5 Hence, (-5, 0) is the point of intersection of X-axis and the line y = x+5. Correct option is D) (-5, 0) |
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271. |
Find a point on the x-axis which is equidistant from the points (7, 6) and (-3, 4). |
Answer» Let A(7, 6) and B(-3, 4) be the given points. Let P(x, 0) be the point on the x-axis such that PA = PB So, PA2 = PB2 (x – 7)2 + (0 – 6)2 = (x + 3)2 + (0 – 4)2 x2 + 49 – 14x + 36 = x2 + 9 + 6x + 16 -20x = -60 x = 3 Therefore, the point on x-axis is (3, 0). |
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272. |
What is the equation of the line passing through (2, –3) and parallel to the y-axis ?(a) y = –3 (b) y = 2 (c) x = 2 (d) x = – 3 |
Answer» (c) x = 2 Slope of y-axis = tan 90º (∵ y-axis ⊥ x-axis) ∴ Equation of line passing through (2, –3) parallel to y-axis is (y + 3) = tan 90º (x – 2) ⇒ (y + 3) = ∞ (x – 2) ⇒ (x – 2) = \(\frac{1}{\infty}\) (y + 3) = 0 ⇒ x = 2. |
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273. |
The distance between two points A(a cosθ, 0), B(0, asinθ) is ………………. A) a B) a2C) √a D) 0 |
Answer» Correct option is (A) a Distance between points \(A\,(a\,cos\theta,0)\;\&\;B\,(0,a\,sin\theta)\) is \(AB=\sqrt{(0-a\,cos\theta)^2+(a\,sin\theta-0)^2}\) \(=\sqrt{a^2\,cos^2\theta+a^2\,sin^2\theta}\) \(=\sqrt{a^2\,(cos^2\theta+sin^2\theta)}\) \(=\sqrt{a^2}\) \((\because cos^2\theta+sin^2\theta=1)\) = a Hence, distance between points \(A\,(a\,cos\theta,0)\;\&\;B\,(0,a\,sin\theta)\) is a. Correct option is A) a |
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274. |
The acute angle which the perpendicular from the origin on the line 7x –3y = 4 makes with the x-axis is:(a) zero (b) positive but not \(\frac{\pi}{4}\)(c) negative (d) \(\frac{\pi}{4}\) |
Answer» (c) negative As the line from the origin is perpendicular to the line 7x – 3y = 4, so its slope = \(\frac{-1}{\text{slope of }\,7x-3y=4}\) Slope of 7x – 3y – 4 = \(\frac{7}{3}\) ∴ Slope of line from origin = \(\frac{-1}{+\frac{7}{3}}\) = \(\frac{-3}{7}\) ∴ tan θ = \(\frac{-3}{7}\), where θ is the angle the line makes with the +ve direction of x-axis ⇒ θ = tan-1 \(\big(\frac{-3}{7}\big)\) = - tan-1 \(\big(\frac{3}{7}\big)\) |
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275. |
Which point on the y-axis is equidistant from (2, 3) and (-4, 1)? |
Answer» Let A (2, 3) and B (-4, 1) be the given points Let the point on y – axis equidistant from the above points be C (0, y) Now, we have AC = √[(0 – 2)2 + (y – 3)2] = √[y2 – 6y + 9 + 4] = √[y2 – 6y + 13] And, BC = √[(0 – (-4))2 + (y – 1)2] = √[y2 – 2y + 1 + 16] = √[y2 – 2y + 17] As AC = BC (given condition) So, AC2 = BC2 y2 – 6y + 13 = y2 – 2y + 17 -4y = 4 y = -1 Therefore, the point on the y-axis is (0, -1). |
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276. |
Find a point which is equidistant from the points A (-5, 4) and B (-1, 6). How many such points are there? |
Answer» Let P(x, y) be the equidistant point from points A (-5, 4) and B (-1, 6). So, the mid-point can be the required point (x, y) = ( (-5 – 1/ 2), (4 + 6)/2 ) (x , y) = (-6/2 , 10/2) = (-3, 5) Thus, the required point is (-3, 5) Now, We also know that, AP = BP So, AP2 = BP2 (x + 5)2 + (y – 4)2 = (x + 1)2 + (y – 6)2 x2 + 25 + 10 + y2 – 8y + 16 = x2 + 2x + 1 + y2 – 12y + 36 10x + 41 – 8y = 2x + 37 – 12y 8x + 4y + 4 = 0 2x + y + 1 = 0 Therefore, all the points which lie on the line 2x + y + 1 = 0 are equidistant from A and B. |
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277. |
Justify that the line AB line segment formed by given points is parallel to Y-axis. What can you say about their slope? Why? |
Answer» In the above problem, all points are of the form (K, y) where K is a fixed number and y is a variable. ∴ All lines in the above problem are parallel to Y – axis. Slope of lines parallel to y – axis are not defined. |
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278. |
What do you observe? |
Answer» We observe that the area formed by above all triangles is zero. |
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279. |
The coordinates of the circumcentre of the triangle whose vertices are (8, 6), (8, –2) and (2, –2).(a) (5, 2) (b) (–2, –5) (c) (0, 0) (d) (5, 0) |
Answer» (a) (5, 2) Let A(8, 6) , B(8, –2) and C(2, –2) be the vertices of the given triangle and P(x, y) be the circum-centre of this triangle. Then, PA2 = PB2 = PC2 Now, PA2 = PB2 ⇒ (x – 8)2 + (y – 6)2 = (x – 8) + (y + 2)2 ⇒ x2 – 16x + 64 + y2 – 12y + 36 = x2 – 16x + 64 + y2 + 4y + 4 ⇒ 16y = 32 ⇒ y = 2. Now, PB2 = PC2 ⇒ (x – 8)2 + (y + 2)2 = (x – 2)2 + (y + 2)2 ⇒ x2 – 16x + 64 + y2 + 4y + 4 = x2 – 4x + 4 + y2 + 4y + 4 ⇒ 12x = 60 ⇒ x = 5. ∴ Co-ordinates of the circumcentre are (5, 2). |
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280. |
Name the quadrilateral ABCD, the coordinates of whose vertices are A(3, 5), B(1, 1), C(5, 3) and D(7, 7).(a) Square (b) Rhombus (c) Rectangle (d) Trapezium |
Answer» (b) Rhombus AB = \(\sqrt{(3-1)^2+(5-1)^2}\) = \(\sqrt{4+16}\) = \(\sqrt{20}\) = \(2\sqrt5\) BC = \(\sqrt{(1-5)^2+(1-3)^2}\) = \(\sqrt{16+4}\) = \(\sqrt{20}\) = \(2\sqrt5\) CD = \(\sqrt{(5-7)^2+(3-7)^2}\) = \(\sqrt{4+16}\) = \(\sqrt{20}\) = \(2\sqrt5\) AD = \(\sqrt{(3-7)^2+(5-7)^2}\) = \(\sqrt{16+4}\) = \(\sqrt{20}\) = \(2\sqrt5\) AC = \(\sqrt{(3-5)^2+(5-3)^2}\) = \(\sqrt{4+4}\) = \(\sqrt{8}\) = \(2\sqrt2\) BD = \(\sqrt{(1-7)^2+(1-7)^2}\) = \(\sqrt{36+36}\) = \(\sqrt{72}\) = \(6\sqrt2\) Now, AB = BC = CD = AD ⇒ All sides are equal Also, AC ≠ BD ⇒ Diagonals are not equal. ⇒ ABCD is a rhombus. |
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281. |
Find the distance between the points (a cos 60°, 0) and (0, a sin 60°). |
Answer» Required distance = \(\sqrt{(0-a\,cos 60°)^2+(a\, sin\,60°-0)^2}\) = \(\sqrt{\big(\frac{-a}{2}\big)^2+\big(\frac{\sqrt3a}{2}\big)^2}\) = \(\sqrt{\frac{a^2}{4}+\frac{3a^2}{4}}=\sqrt{\frac{4a^2}{4}}\) = a units. |
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282. |
Find the value of x if the distance between the points (2, –11) and (x, –3) is 10 units. |
Answer» Given, \(\sqrt{(x-2)^2+(-3-(-11))^2} = 10\) ⇒ \(\sqrt{(x-2)^2+64} = 10\) ⇒ \(\sqrt{x^2-4x+4+64}=10\) ⇒ x2 – 4x + 68 = 100 ⇒ x2 – 4x – 32 = 0 ⇒ (x – 8) (x + 4) = 0 ⇒ x = 8 or – 4 |
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283. |
If A (–2, –1), B (a, 0), C (4, b) and D (1, 2) are the vertices of a parallelogram the values of a and b respectively are (a) 3, 1 (b) –3, 1 (c) 1, 3 (d) –1, –3 |
Answer» (c) 1, 3 The diagonals of a parallelogram bisect each other, therefore co-ordinates of mid-points of both the diagonals are the same co-ordinates of mid-point of diagonal AC = \(\bigg(\frac{4-2}{2},\frac{b-1}{2}\bigg) \) = \(\bigg(1,\frac{b-1}{2}\bigg) \) Co-ordinate of mid-point of diagonal BD = \(\bigg(\frac{1+a}{2},\frac{2-0}{2}\bigg) \) = \(\bigg(\frac{1+a}{2},1\bigg) \) ⇒ \(\frac{1+a}{2}=1\) and \(\frac{b-1}{2}=1\) ⇒ 1 + a = 2 and b – 1 = 2 ⇒ a = +1 and b = 3 |
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284. |
Show that the points (1, –1), (5, 2) and (9, 5) are collinear. |
Answer» Let P(1, –1), Q(5, 2) and R(9, 5) be the given points. Then PQ = \(\sqrt{(5-1)^2+(2+1)^2}\) = \(\sqrt{16+9}\) = \(\sqrt{25}\) = 5 QR = \(\sqrt{(9-5)^2+(5-2)^2}\) = \(\sqrt{16+9}\) = \(\sqrt{25}\) = 5 PR = \(\sqrt{(9-1)^2+(5+1)^2}\) = \(\sqrt{64+36}\) = \(\sqrt{100}\) = 10 ⇒ PQ + QR = PR ⇒ P, Q, R are collinear points. |
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285. |
If a = b = c, prove that the points (a, a2), (b,b2),(c, c2) can never be collinear. |
Answer» Area of the triangle having vertices (x1, y1), (x2, y2) and (x3, y3) is given by Area of △ = \(\frac{1}2[x_1(y_2 - y_3) + x_2(y_3 - y_1) + x_3(y_1-y_2)]\) For points to be collinear, the Area enclosed by them should be equal to 0 ∴ For given points, Area = \(\frac{1}2[a(b^2 - c^2) + b(c^2- a^2) + c(a^2-b^2)]\) Area = \(\frac{1}2\) |(b – c)(a - b)(c – a)| Area ≠ 0 Also it is given that a ≠ b ≠ c, Hence area of triangle made by these points is never zero. Hence given points are never collinear. |
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286. |
Prove that the points (a, 0), (0, b) and (1, 1) are collinear if,\(\frac{1}a+\frac{1}b\) = 1 |
Answer» Let three given points be A(a,0), B(0,b) and C(1,1). Area of the triangle having vertices (x1,y1), (x2,y2) and (x3,y3) = \(\frac{1}2\) |x1(y2 - y3)+x2(y3 - y1)+x3(y1 - y2)| Area of ∆ABC = \(\frac{1}2\) |a(b – 1) + 1(0 -b)| = \(\frac{1}2\) | ab – a –b| Here given that \(\frac{1}a+\frac{1}b\) = 1 ∴ \(\frac{a+b}{ab}\) = 1 ∴ a + b = ab Now, Area of ∆ABC = \(\frac{1}2\) | ab - (a + b)| = \(\frac{1}2\) | ab – ab| = \(\frac{1}2\) | 0 | = 0 sq. units We know that if area enclosed by three points is zero, then points are collinear. Hence, given three points are collinear. |
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287. |
Four points A (6, 3), B (-3, 5), C (4, - 2) and D (x, 3x) are given in such a way that \(\frac{△DBC}{△ABC}\) = \(\frac{1}2\) , find x. |
Answer» Four points A (6, 3), B (−3, 5) C (4, −2) and D(x, 3x) Area of the triangle having vertices (x1,y1), (x2,y2) and (x3,y3) = \(\frac{1}2\) |x1(y2-y3)+x2(y3-y1)+x3(y1-y2)| Area of ∆ABC = \(\frac{1}2\) |6(5 – (- 2)) - 3(-2 -3) + 4(3 – 5)| = \(\frac{1}2\) |42 + 15 -8| = \(\frac{49}2\) sq. units Area of ∆DBC = \(\frac{1}2\) |x(5 – (-2)) + 3(-2 -3x) + 4(3x - 5))| = \(\frac{1}2\) |7x +6 + 9x + 12x - 20| = \(\frac{1}2\) | 28x -14| = ± 7(2x -1 ) It is given that \(\frac{△DBC}{△ABC}\) = \(\frac{1}2\) ∴2 × ∆DBC = ∆ABC 2 × (± 7(2x -1 )) = \(\frac{49}2\) ∴ ± 4(2x -1 ) = 7 ∴ 4(2x -1 ) = 7 or -4(2x -1 ) = 7 ∴ 8x – 4 =7 or -8x + 4 =7 ∴ 8x =11 or -8x =3 ∴x = \(\frac{11}8\) or x = \(\frac{-3}8\) Hence, the value of x is \(\frac{11}8\) or \(\frac{-3}8\) |
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288. |
Find the values of y for which the distance between the points P (2, - 3) and Q (10, y) is 10 units. |
Answer» Given: the distance between the points P (2, -3) and Q (10, y) is 10 units. To find: The value of y. Solution: Coordinates are P (2, - 3) and Q (10, y) We use distance formula \(\sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}\) to find the distance between two points. Since PQ = 10 units S0, \(\sqrt{(10 - 2)^2 + (y + 3)^2}\) = 10 On squaring both sides, we get (10 - 2)2 + (y + 3)2 = 100 ⇒ 82 + (y + 3)2 = 100 ⇒ 64 + y2 + 6y + 9 = 100 ⇒ 73 + y2 + 6y = 100 ⇒ 73 + y2 + 6y -100 = 0 ⇒ y2 + 6y - 27 = 0 In factorization, we write the middle term of the quadratic equation either as a sum of two numbers or difference of two numbers such that the equation can be factorized. ⇒ y2 + 9y - 3y - 27 = 0 ⇒y(y + 9) - 3(y + 9) = 0 ⇒(y - 3)(y + 9) = 0 ⇒y = 3, - 9 |
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289. |
The centre of a circle is (x – 2, x + 1) and it passes through the points (4, 4). Find the value (or values) of x, if the diameter of the circle is of length 2 5 units .(a) 1 or 3 (b) –1 or 4 (c) 5 or 4 (d) 3 or –2 |
Answer» (c) 5 or 4 Radius of the circle = Dist. between the centre and given pt. on the circle = \(\sqrt{(x-2-4)^2+(x+1-4)^2}\) = \(\sqrt{(x-6)^2+(x-3)^2}\) = \(\sqrt{x^2-12x+36+x^2-6x+9}\) = \(\sqrt{2x^2-18x+45}\) Given, diameter = 2√5 ⇒ radius = \(\frac12\times2\sqrt5 = \sqrt5\) ∴ \(\sqrt{2x^2-18x+45}\) = √5 ⇒ 2x2 – 18x + 45 = 5 ⇒ 2x2 – 18x + 40 = 0 ⇒ x2 – 9x + 20 = 0 ⇒ (x – 5) (x – 4) = 0 ⇒ x = 5 or 4 |
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290. |
See Fig., and write the following: |
Answer» (i) The coordinates of B : (-5, +2) (ii) The coordinates of C. : (+5, -5) (iii) The point identified by the coordinates (-3, -5) : E. (iv) The point identified by the coordinates (2, -4) : G. (v) The abscissa of the point D : 6 (vi) The ordinate of the point H: -3 (vii) The coordinates of the point L : (0, +5) (viii) The coordinates of the point M : (-3, 0). |
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291. |
Write the answer of each of the following questions : (i) What is the name of horizontal and the vertical lines drawn to determine the position of any point in the Cartesian plane ? (ii) What is the name of each part of the plane formed by these two lines ? (iii) Write the name of the point where these two lines intrsect. |
Answer» (i) In a Cartesian plane, to determine the position of any point, horizontal line is called x-axis. Vertical line is y The y-coordinate is also called the ordinate. Horizontal line → xOx’ Vertical line → yOy’ (ii) The name of each part of the plane formed by these two lines is called Quadrant. I Quadrant → xOy II Quadrant → yOx’ III Quadrant → x’Oy’ IV Quadrant → y’Ox (iii) The name of the point where these two lines intersect is called origin. Coordinates of origin are (0. 0). |
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292. |
The value of p for which the points (–1, 3), (2, p) and (5, –1) are collinear is(a) –1 (b) 2 (c) \(\frac13\) (d) 1 |
Answer» (d) 1 For collinearity of points A (–1, 3), B (2, p), C (5, –1) area of ΔABC should be zero, i.e., \(\frac12\) | - 1(p +1) + 2(-1 -3) + 5(3-p) | = 0 ⇒ – p – 1 – 8 + 15 – 5 p = 0 ⇒ – 6 p + 6 = 0 ⇒ –6 p = – 6 ⇒ p = 1. |
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293. |
Find the centre of the circle passing through (6, - 6), (3, - 7) and (3, 3). |
Answer» Coordinates of points on a circle are A(6, -6), B(3, -7) and C(3, 3). Let the coordinates of the centre of the circle be O(x, y) Using distance formula = \(\sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}\) Since the distance of the points A, B and C will be equal from the center, therefore ⇒ OA = OC \(\sqrt{(x - 6)^2 + (y + 6)^2}\) = \(\sqrt{(x - 3)^2 + (y - 3)^2}\) On squaring both sides, we get (x - 6)2 + (y + 6)2 = (x - 3)2 + (y - 3)2 x2 - 12x + 36 + y2 + 12y + 36 = x2 - 6x + 9 + y2 - 6y + 9 x - 3y = 9........(1) Similarly, OA = OB \(\sqrt{(x - 6)^2 + (y + 6)^2}\) = \(\sqrt{(x - 3)^2 + (y + 7)^2}\) On squaring both sides, we get (x - 6)2 + (y + 6)2 = (x - 3)2 + (y + 7)2 x2 - 12x + 36 + y2 + 12y + 36 = x2 - 6x + 9 + y2 + 14y + 49 3x + y + 7.......(1) Solving eqn (1) and (2), we get x = 3; y = - 2 Coordinates of circum center are (3, - 2) |
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294. |
Two opposite vertices of a square are (-1, 2) and (3, 2). Find the coordinates of other two vertices. |
Answer» The coordinates are A(-1, 2) and C(3, 2). Let the coordinates of the vertex B are (x, y) AB = BC Using distance formula = \(\sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}\) \(\sqrt{(x + 1)^2 + (y - 2)^2}\) = \(\sqrt{(x - 3)^2 + (y - 2)^2}\) On squaring both sides, we get (x + 1)2 + (y - 2)2 = (x - 3)2 + (y - 2)2 x2 + 2x + 1 + y2 - 4y + 4 = x2 - 6x + y2 - 4y + 4 x = 1 In ΔABC AB2 + BC2 = AC2 [Using Pythagoras theorem] 2AB2 = AC2 [Since AB = BC] 2[(x + 1)2 + (y - 2)2] = (3 + 1)2 + (2 - 2)2 2[x2 + 2x + 1 + y2 - 4y + 4] = 16 x2 + 2x + 1 + y2 - 4y + 4 = 8 x2 + 2x + y2 - 4y = 3 On substituting x = 1 1 + 2 x 1 + y2 - 4y = 3 y2 - 4y = 0 y(y - 4) = 0 y = 0, 4 Other coordinates are (1, 0) and (1, 4) |
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295. |
The co-ordinates of the vertices of a side of square are (4, –3) and (–1, –5). Its area is(a) 2 √29 sq. units (b) \(\frac{\sqrt{89}}{2}\) sq. units (c) 89 sq. units (d) 29 sq. units |
Answer» (d) 29 sq. units Length of a side of the square = \(\sqrt{(-1-4)^2+(-5+3)^2}\) = \(\sqrt{25+4} = \sqrt{29}\) units. ∴ Area = (Side)2 = \((\sqrt{29})^2\) sq. units = 29 sq. units |
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296. |
If the points (2, 1) and (1, – 2) are equidistant from the point (x, y), show that x + 3y = 0. |
Answer» (x, y) is equidistant from the points (2, 1) and (1, –2) ⇒ Distance between (x, y) and (2, 1) = Distance between (x, y) and (1, –2) ⇒ \(\sqrt{(x-2)^2+(y-1)^2}\) = \(\sqrt{(x-1)^2+(y+2)^2}\) ⇒ x2 – 4x + 4 + y2 – 2y + 1 = x2 – 2x + 1 + y2 + 4y + 4 ⇒ – 4x + 2x – 2y – 4y = 0 ⇒ –2x – 6y = 0 ⇒ x + 3y = 0 |
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297. |
The equation of the line having slope 1 and passing through (3, 2) is A) x + y = 1 B) x – y = 1 C) 2x – y + 1 = 0 D) x – 2y + 1 = 0 |
Answer» Correct option is (B) x – y = 1 Given that slope of required line is m = 1 & it passes through point (3, 2). Let equation of the required line is \(y=mx+c\) \(\Rightarrow\) \(y=x+c\) \((\because m=1)\) Put x = 3 & y = 2 \((\because\) Required line passes through (3, 2)) \(\therefore2=3+c\) \(\Rightarrow c=2-3=-1\) Put c = -1 in \(y=x+c,\) we get \(y=x-1\) \(\Rightarrow x-y=1\) Hence, the equation of required line is \(x-y=1.\) Correct option is B) x – y = 1 |
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298. |
Find the point on the x-axis which is equidistant from the points (2, -5) and (-2, 9). |
Answer» Let point P(x, 0) is on x-axis and equidistant from A(2, -5) and B (-2, 9) PA = PB or PA2 = PB2 (2 – x)2 + (– 5 – 0)2 = (– 2 – x)2 + (9 – 0)2 (2 – x)2 + (– 5)2 = (– 2 – x)2 + (9)2 29 + x2 – 4x = 85 + x2 + 4x 56 = – 8x or x = – 7 The point on ×-axis is (– 7, 0) |
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299. |
Find the point which represents three-fourth of the distance from the point (3, 2) to the point (-5, 6). |
Answer» Mid point of the line segment joining the points (3, 2) and (-5, 6) = [(x1 + x2)/2, (y1 + y2)/2] = [(3 - 5)/2, (2 + 6) /2] = (-1, 4) Mid point of the line segment joining (3, 2) and (-5, 6) is at one-half of the distance from (3, 2). Midpoint of the segment joining the points (-1, 4) and ((-5, 6) = [(-1 + 5)/2, (4 + 6) /2] = (2, 5) The point (2, 5) represents three-fourth of the distance from the point (3, 2) to the point (-5, 6). |
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300. |
Students of a school are standing in rows and columns in their playground for drill practice. A, B, C and D are the position of the four students as shown in the figure.If Mohit wants to stand in such a way that he is equidistance from each of the four students A, B, C and D then what are the coordinate of his position ?(A) (6, 6)(B) (7, 5)(C) (6, 4)(D) (4, 6) |
Answer» The correct option is: (B) (7, 5) Explanation: Mohit's position will be (7, 5). |
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