Given
centre of circle O(-5,-9)=O(x0,y0)
point on circle P(-2,-13)
Standard equation of circle:
(x-x0)^2+(y-y0)^2=r^2
r=radius of circle
= (distance OP)
= sqrt((-2-(-5))^2+(-13-(-9))^2)
=sqrt(3^2+(-4)^2)
=sqrt(25)
=>
r^2=(sqrt(25))^2=25
Equation of circle
(x-x0)^2+(y-y0)^2=r^2
(x+5)^2+(y+9)^2=25 ............... standard equation of circle
