The circles whose equations are and will touch one another externally

MATHEMATICS · Single correct · ISC · Mathematics · Coordinate Geometry · Coordinate Geometry

Problem

The circles whose equations are x2+y2+c2=2axx^2 + y^2 + c^2 = 2ax and x2+y2+c2−2by=0x^2 + y^2 + c^2 - 2by = 0 will touch one another externally, if (1) 1b2+1c2=1a2\frac{1}{b^2} + \frac{1}{c^2} = \frac{1}{a^2} (2) 1c2+1a2=1b2\frac{1}{c^2} + \frac{1}{a^2} = \frac{1}{b^2} (3) 1a2+1b2=1c2\frac{1}{a^2} + \frac{1}{b^2} = \frac{1}{c^2} (4) 1b2+1c2=2a2\frac{1}{b^2} + \frac{1}{c^2} = \frac{2}{a^2}

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