If the power of the point ( 1 , 6 ) with respect to the circle x 2 + y 2 + 4 x - 6 y - a = 0 is - 16 then a ' ' equals

Question

If the power of the point ( 1 , 6 ) with respect to the circle x 2 + y 2 + 4 x - 6 y - a = 0 is - 16 then a ' ' equals, 5, 11, 21, 6

MARKS App · Accepted Answer

As we know, power of a point x 1 , y 1 w.r.t. the circle is x 1 2 + y 1 2 + 2 g x 1 + 2 f y 1 + C So, Power of point 1 , 6 = 1 2 + 6 2 + 4 × 1 - 6 × 6 - a ⇒ - 16 = 5 - a ⇒ a = 21

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