The Lesson
A rectangle is a four sided shape with four right angles.Dictionary Definition
The Oxford English Dictionary defines a rectangle as "a plane figure with four straight sides and four right angles, opposite sides being parallel and equal in length; especially one in which adjacent sides are unequal, as contrasted with a square."Properties of Rectangles

Opposite sides of a rectangle are of equal length.

All angles in a rectangle are right angles.

Opposite sides of a rectangle are parallel.

All angles of a rectangle add up to 360°.

The diagonals of a rectangle are equal in length. They bisect each other. They cross each other halfway along their lengths.
The Perimeter of a Rectangle
The perimeter of a rectangle is given by the formula:In this formula, b is the length of the base and h is the height of the rectangle.
The Area of a Rectangle
The area of a rectangle is given by the formula:In this formula, b is the length of the base and h is the height of the rectangle.
Read more about how to find the area of a rectangle