How to use Pythagorean theorem with a rectangle? I have all measurements but i don't understand how to use it with the Pythagorean theorem

Slice the rectangle in half diagonally. If they've already given you two of the measurements, then use the Pythagorean Theorem of a triangle to find the missing measurement. Then multiply the measurements of the first triangle by two. Now, you have the Pythagorean Theorem of a rectangle.