A circle S passes through the point (0, 1) and is orthogonal to the circles (x – 1)2 + y2 = 16 and x2 + y2 = 1. Then
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x2 + y2 + 2gx + 2fy + c = 0 is required circle
⇒ 2g1g2 + 2f1f2 = c1 + c2
0 + 0 = c + (–1) ⇒ c = 1 .....(1)
and x2 + y2 – 2x – 15 = 0
2 (–1) g + 0 = 1 + (–15)
– 2g = – 14
g = 7 .....(2)
x2 + y2 + 14x + 2fy + 1 = 0 satisfies (0, 1)
0 + 1 + 0 + 2f + 1 = 0 ⇒ f = – 1
Circle is x2 + y2 + 14x – 2y + 1 = 0
Centre: (–7, 1)
option (B), (C)