# Perimeter of a rectangle

A rectangle is a quadrangle with four right angles and sides that are equal in pairs. The perimeter of a rectangle is the sum of the lengths of its sides. For the calculation, you can specify either the length and width of the rectangle, or its diagonal and one of the sides.

**The perimeter of a rectangle knowing two sides**

**Side a**

**Side b**

**The perimeter of the rectangle knowing the diagonal and the side**

**Side a**

**Diagonal d**