Equation of circle is x2+y2=25 . . . (i) Polar equation of a circle with respect to the point (1,a) and (b,2) is x+ay=25 . . . (ii) bx+2y=25 . . . (iii) Since, (1,a) and (b,2) are the conjugate point of a circle, therefore point (1,a) satisfy the equation (iii), we get ‌b+2a=25 ‌⇒‌‌2b+4a=50 ‌