Given, a general second-degree equation ax2+2hxy+by2+2gx+2fy+c=0(a≠0) represent a circle. The general equation of any type of circle is represented by: x2+y2+2gx+2fy+c=0 , for all values of g, f and c. ⇒x2+2hxy+y2+2gx+2fy+c=0, Comparing both equations, we get ⇒ a = 1, b = 1, 2h = 0 ⇒ a = b and h = 0