Circle passes through (0,0) so, x2 + y2 + 2gx + 2fy = 0 (2, 6) & (6, 2) lies on it so, 22 +62 + 4g + 12f = 0 .... (1) 22 + 62 12g + 4f = 0 .... (2) ⇒ From (1) & (2) g = f = –5/2 Eqn. of circle is x2 + y2 – 5x – 5y = 0 For y = 0, x (x - 5) = 0 ⇒ x = 0, x = 5 OP = 5