Standard equation of cirlce- \[(x-a)^{2}+(y-b)^{2}=r^{2} \]
where center is at (a,b) and x , y is any point on the circumference of the circle.
and r is radius of the circle.
If center is taken at origin then equation can be written as\[(x)^{2}+(y)^{2}=r^{2} \]
