How to do you find the radius of a square with a circle inscribed into it?

When used in reference to a square, the radius is the distance from the center of the square to any of the four vertices, or where two sides intersect. Because a square has four right angles, you can find the diameter of the square using the Pythagorean Theorem. Multiply the side length of the square by itself.
                                   -google

and radius of a circle is 2 pi R the formula your welcome;) love u