A L W where A is the area L is the length W is the width and means multiply. The diagonal of a rectangle divides it into two congruent right triangles. In order to prove this works work out an area of a rectangle using that formula.
D sqrt l 2b 2.
Using the diagonal and side length formula. For example if the area is 60 and the width is 5 your equation will look like this. The formula is where equals the length of the rectangles diagonal equals the length of the rectangle and equals the width of the rectangle. The formulas for the perimeter P and the area A of the rectangle are used to write equations as follows.