1.

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



Discussion

No Comment Found

Related InterviewSolutions