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TS EAMCET · Maths · Circle

The value of \(a\), such that the power of the point \((1,6)\) with respect to the circle \(x^2+y^2+4 x-6 y-a=0\), is -16 , is

  1. A 7
  2. B 11
  3. C 13
  4. D 21
Verified Solution

Answer & Solution

Correct Answer

(D) 21

Step-by-step Solution

Detailed explanation

Given equation of the circle is \[ x^2+y^2+4 x-6 y-a=0 \] We know that, power of point \(P(1,6)\) w.r.t. the circle \[ \begin{array}{rrrr} & x^2+y^2+4 x-6 y-a \text { is }-16 \\ \therefore & 1+36+4-36-a=-16 \\ \Rightarrow & 5-a=-16 \\ \Rightarrow & a & =21 \end{array} \]