[tex]Equation\ of\ circle\\\\\
r^2=(x-a)^2+(y-b)^2\\\\
a,b- \ coordinates\ of\ center\ of\ circle\\\\\
(a,b)=(-1,-3)\\\\
r^2=(x+1)^2+(y+3)^2\\\\\
Substituting\ point\ (3,0)\\\\
r^2=(3+1)^2+(0+3)^2\\\\
r^2=4^2+3^2\\\\
r^2=16+9=25\\
r=5\\\\
Answer:\ \ 25=(x+1)^2+(y+3)^2[/tex]
