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Find the equation of the circle passing through the point (0,5) and (6, 1) and has its centre on the line 12x + 5y = 25. |
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Answer» Let the equation of the required circle is x2 + y2 + 2gx + 2fy + c = 0 given that this Equation passes through the points (0,5) and (6, 1) ∴ (0,5) 02 + 52 + 2(0)g + 2(5)f + C=0 10f + C + 25 = 0 (6, 1) 62 + 12 + 2.6g + 2.1f+C = 0 …. (1) 12g + 2f + C + 37 = 0 …. (2) Also the centre (-g, -f) lies on the line 12x + 5y – 25 = 0 ∴ -128 – 5f – 22 = 0 …. (3) Equation (2) – Equation (1) gives 12g – 8f + 12 = 0 …(4) Adding equations 3 and 4 we get -13f – 13 = 0 → f = \(\frac{13}{-13}\) - 1 ⇒ f = -1 From equation 4 12g = 8f + 12 = – 8 + 12 = 4 g = \(\frac{1}{3}\) 10 + C + 25 = 0 ⇒ c = -15 ∴ Required equation is x2 + y2 + 2\(\frac{1}{3}\)x + 2(-1)y -15 = 0 ⇒ 3x2 + 3y2 + 2x – y – 45 = 0 |
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