Question

A circle has the equation `(x + 1)^2 + (y - 3)^2 = 16`. What are the coordinates of its center and length of radii?

Answer 1

Have a look:

Explanation:

You can think at the general equation of a circle:
`(x-h)^2+(y-k)^2=r^2`
where:
`h,k` are the coordinates of the center;
`r` is the radius.

In your case:

`h=-1`
`k=3`
`r=sqrt(16)=4`