Question

The general form of the Quetion of a circle is ax^2+by^2+cx+dy+e=0 where a=b=0 If the circle has a radius of three units and the center lies on the Y axis Which set of values of a, B, C, D, and E Might correspond to the circle

Answer 1

Option C

Explanation:

C. A = 1, B = 1, C = 0, D = -8, and E = 7

Answer 2

a =1 ,b =1 ,c =0 , d =-2k and e =
`k^(2) -9`

Explanation:

Equation of circle with radius 3 units and center on Y axis is always of the form

`(x-0)^2+ (y-k)^2 = r^2 \\`

where r = 3

on simplifying it we get

`x^(2) +y^(2) -2yk+k^(2) =9`

`x^(2) +y^(2) -2yk+k^(2) -9`=0

on comparing it with given general equation we get

a =1 ,b =1 ,c =0 , d =-2k and e =
`k^(2) -9`

where k can be any real number