UPSC NDA Math Model Paper 8

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