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AP EAMCET · Maths · Circle

If the circles \(x^2+y^2-4 x+2 f y+1=0\) and \(x^2+y^2+\) \(2 \mathrm{gx}-4 \mathrm{y}-1=0\) cut orthogonally, then \(\mathrm{r}_1^2+\mathrm{r}_2^2-8=\)

  1. A \(\mathrm{g}^2\)
  2. B \(-\mathrm{f}^2\)
  3. C \(2 \mathrm{~g}^2\)
  4. D \(-2 \mathrm{f}^2\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(2 \mathrm{~g}^2\)

Step-by-step Solution

Detailed explanation

Let \(S_1: x^2+y^2-4 x+2 f y+1=0\) ...(i) \(S_2: x^2+y^2+2 g x-4 y-1=0\) ...(ii) \(\begin{aligned} & \mathrm{g}_1=2, \mathrm{f}_1=\mathrm{f}, \mathrm{c}_1=1 \\ & \mathrm{~g}_2=\mathrm{g}, \mathrm{f}_2=2, \mathrm{c}_2=-1\end{aligned}\) \(\because\) Circle (i) \& (ii) are…