Question

Find the equation of the circle which have radius $\sqrt{13}$ and center at $(1,1)$.

Answer 1

Radius of circle $\sqrt{13}$

The center of circle is $(1,1)$

The equation of circle is $(x-h{)}^2+(y-k{)}^2=r^2(x-1{)}^2+(y-1{)}^2=(\sqrt{13}{)}^2{x}^2+y^2-2x-2y+1+1=13x^2+y^2-2x-2y-11=0$