Are the diagonals of a rectangle equal in length proof that?

Yes, the diagonals of a rectangle are equal in length. This can be proven using the Pythagorean theorem. In a rectangle, the diagonals create two congruent right triangles, where the lengths of the sides are the width and height of the rectangle. Since the legs of these triangles are equal for both diagonals, their hypotenuses (the diagonals) must also be equal.