Rhombus

Rhombus, a two-dimensional figure with four sides of equal length. A rhombus is thus a quadrilateral, because it has four sides, and a parallelogram, because its opposite sides are parallel. Rectangular rhombuses—those whose interior angles are right angles (90°)—are squares. If each side of a rhombus has length s, the perimeter of the rhombus is 4s. The height of a rhombus is the shortest distance between opposite sides, which is equal to the length of a line that is perpendicular to both opposite sides. The area of a rhombus is equal to the length of a side times the height: A = sh.