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