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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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