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AP EAMCET · Maths · Circle

The radius of the circle passing through the points of intersection of the circles \(x^2+y^2+2 x+4 y+1=0, x^2+y^2-2 x-4 y-4=0\) and intersecting the circle \(x^2+y^2=6\) orthogonally is

  1. A \(\sqrt{19}\)
  2. B \(5\)
  3. C \(\sqrt{39}\)
  4. D \(4\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(\sqrt{39}\)

Step-by-step Solution

Detailed explanation

Let the required circle be \(S\). The equation of a circle passing through the intersection of \(S_1 \equiv x^2+y^2+2 x+4 y+1=0\) and \(S_2 \equiv x^2+y^2-2 x-4 y-4=0\) is \(S_1+\lambda S_2=0\). \( (x^2+y^2+2x+4y+1) + \lambda(x^2+y^2-2x-4y-4) = 0 \)…