Question

What is the standard form of the equation of a circle with with the centre (-2,3) and radius 6?

Answer 1

`(x+2)^2+(y-3)^2=36`

Explanation:

The equation for a circle is `(x-h)^2+(y-k)^2=r^2`, where `(h,k)` is the center of the circle and `r` is the radius.

This translates into: `(x+2)^2+(y-3)^2=36`

Common mistakes when writing the equation are not remembering to flip the signs of `h` and `k`. Notice that the center is `(-2,3)`, but the circle's equation has the terms `(x+2)` and `(y-3)`. Also, don't forget to square the radius.