# Sides of a Rectangle

How to solve the sides of a rectangle problems: property, example, and its solution.

## Definition

A rectangle is a parallelogram

whose interior angles are all right angles.

So a rectangle has all the properties of a parallelogram.

## Property

Just like the sides of a parallelogram,

the opposite sides of a rectangle are congruent.

## Example

The blue sides are the opposite sides of the rectangle.

So *AB* = *DC* = 12.

See △*ADC*.

Its legs are 5 and 12.

So it's a (5, 12, 13) triangle.

So *AC* = 13.