x2+y2=a2+b2
circle with center (0,0) and radius √a2+b2
Ques) The equation (x2-a2) 2 + (y2-b2) 2 = 0 represents points
(a) which are collinear
(b) which lie on a circle with centre at (0,0)
(c) which lie on a circle with centre at (a,b)
(d) none of the above
this is not the equation of a circle.
sum of two squares can never be 0 provided they are themselves 0.
hence it represent 4 points in the cartesian system
x=+a,-a and
y=+b,-b