Question

What is the standard form that has a center (1,3) and a radius of 9

Answer 1

$\huge\boxed{(x-1)^2+(y-3)^2=9^2}$

Start with the standard form of a circle, where $(h,k)$ is the center of the circle and $r$ is the radius.

$(x-h)^2+(y-k)^2=r^2$

Plug in the known values.

$\boxed{(x-1)^2+(y-3)^2=9^2}$

This is the circle's equation in standard form.