Question

How do you convert `r^2 = x^2 + y^2` into a cartesian equation?

Answer 1

`y=+-sqrt(r^2-x^2)`

Explanation:

Making `y` the subject of the formula gives that
`y=+-sqrt(r^2-x^2)`.

This is the equation of a circle centred at the origin `(0,0)` and having radius `r`.