Equation of circle ‌(x−c)2+(y−0)2=r2 ⇒‌‌x2+c2−2xc+y2=r2 Circle passes through (0,a) c2+a2=r2.....(i) Circle also passes through (b,h), b2+c2−2bc+h2=r2 Substituting value of r2 from Eq. (i), ‌b2+c2−2bc+h2=c2+a2 ⇒‌‌2bc=b2+h2−a2 ⇒c=‌