# Rectangle

## Rectangle

Quadrilateral in which opposite sides are congruent and the four angles are right angles.

The length of a rectangle is the longer of its two dimensions. The width is the shorter dimension..

For measurement purposes, a distinction is sometimes made between the base b and the height h of a rectangle : Either side of a rectangle may be used as a base; the adjacent side will then be the corresponding height.

### Properties

Based on its properties, a rectangle belongs to the larger category of convex quadrilaterals, which are trapezoids and parallelograms.

• Its two diagonals are congruent.
• Its opposite sides are parallel and congruent.
• A rectangle has two lines of symmetry.
• A rectangle is equiangular.

### Formulas

• The perimeter P of a rectangle with a length of l and a width of w is : P = 2 × (l + w).
• The area A of a rectangle with a length of l and a width of w is : A = l × w.

### Example

The opposite sides of this rectangle are congruent.
Its four angles are right angles. ### Educational note

• A rectangle is a quadrilateral, since it is a parallelogram. Like a parallelogram, its sides are parallel in pairs. A parallelogram is also a trapezoid, as it has at least one pair of parallel sides.
• It may also be noted that a square is a rectangle, as all the angles in a square are right angles.