A quadrilateral with four right angles is called a rectangle (or) A parallelogram each of whose angles measures 90° is called a rectangle. To find the area of a rectangle, multiply the length by the width. If a rectangle has an area of 'A' square units, a length of 'l' units and a width of 'w' units, then A = lw.

A square is a rectangle with four equal sides. To find the area of a square, multiply the length of one side by itself. If a square has an area of 'A' square units and length of a side 's' units, then A = s × s = s2.