How do you find the radius of a semicircle using its perimeter?

To find the radius of a semicircle using its perimeter, first note that the perimeter ( P ) of a semicircle is given by the formula ( P = r + \pi r ), where ( r ) is the radius. This simplifies to ( P = r(1 + \pi) ). Rearranging this equation, you can solve for the radius by using ( r = \frac{P}{1 + \pi} ). Thus, if you know the perimeter, you can easily calculate the radius.