Question

Find the equation of the circle passing through two points on y axis at distance 3 from the origin and having radius 5

Answer 1

the general eq. of acircle is x^2+y^2+2gx+2fy+c=0

the 2 points are  (0,3) and (0,-3)

substitute the 2 eqs into the general eq. and solve for c

after finding the value of c substitute it into the general eq. to find the value of g

eq. of radius is (g^2+f^2-c)^1/2=5

substitute the values of g and c to find f

finally substitute the values  of g f and c into the gen. eq. to find the eq. of the circle