AP EAPCET 19-Aug-2021 Shift 2 Paper

Given, radius =5
and points on X-axis at 4 units distance from origin be (−4,0) and (4,0).
Let equation of circle be
x2+y2+2gx+2fy+c=0 ...(i)
Equation (i) passes through (−4,0) and (4,0)
∴ 16−8g+c=0
and16+8g+c=0
On solving, we have
c=−16,9=0
∴ radius =5
⇒√g2+f2−c=5
or f2+16=25
or f = ±3
∴ Required equation of circle
x2+y2±6y−16=0