Question

Find the equation of the circle whose centre is $(-1,2)$ and which passes through $(5,6)$.

Answer 1

Equation of circle with center $(-1,2)$ is : $(x+1{)}^2+(y-2{)}^2=r^2$

It passes through $(5,6)$

$\Rightarrow (5+1{)}^2+(6-2{)}^2=r^2$

$\Rightarrow r=\sqrt{52}$

$\Rightarrow$equation of circle : $(x+1{)}^2+(y-2{)}^2=52$