[Math] How to find the equation of a circle, given radius and centre coordinates

Question

Say I am asked to find, in expanded form without brackets, the equation of a circle with radius 6 and centre 2,3 – how would I go on about doing this?

I know the equation of a circle is $x^2 + y^2 = r^2$, but what do i do with this information?

Answer 1

The equation of a circle with centre $(a,b)$ and radius $r$ is $(x-a)^2+(y-b)^2=r^2$.