Question

The radius of a circle which touches y-axis at (0, 3) and cuts intercept of 8 unit with x-axis, is

Answer 1

Answer:

Equation of circle touches y-axis at (0,3) is

(x−a) 2 +(y−3) 2 =a 2x 2 +y 2−2ax−6y+9=0

Since the length of intercept on x-axis at this circle is 8 unit.

2 (a 2 −9) =8

a 2 −9 =4a 2 −9=16a 2 =16+9⇒a= 25

=5(a>0)

required equation is

x 2 +y 2 −10x−6y+9=0

compare this with given equation, given

g=−5;f=−5c=9

∴g+f+=−5−3+9=1

Explanation:

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