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COMEDK · Maths · 12. Circle

If the circles \(x^{2}+y^{2}+2 g x+2 f y=0\) and \(x^{2}+y^{2}+2 g^{\prime} x+2 f^{\prime} y=0\) touch each other, then

  1. A \(f g=f^{\prime} g^{\prime}\)
  2. B \(f^{\prime} g=f g^{\prime}\)
  3. C \(f f^{\prime}=g g^{\prime}\)
  4. D None of these
Verified Solution

Answer & Solution

Correct Answer

(B) \(f^{\prime} g=f g^{\prime}\)

Step-by-step Solution

Detailed explanation

For given condition, \[ \begin{aligned} \frac{2 g}{2 g^{\prime}} &=\frac{2 f}{2 f^{\prime}} \\ \Rightarrow \quad f^{\prime} &=f g^{\prime} \end{aligned} \]