What is a Rectangle?

A rectangle is a four-sided polygon with opposite sides that are equal in length and all angles that are right angles (90 degrees). It is one of the most common shapes in geometry and is frequently encountered in everyday life, such as in the shape of a book, a television screen, or a piece of paper. The two primary dimensions of a rectangle are its length and width.

To understand a rectangle fully, we often calculate its key components: the area, perimeter, and diagonal. These components help us quantify the space inside the rectangle, the distance around it, and the length of the line connecting opposite corners, respectively.

Components of a Rectangle

Let’s explore the three main components of a rectangle: area, perimeter, and diagonal. We’ll also provide an example for each using a rectangle with a length of 5 meters and a width of 3 meters.

1. Area

The area of a rectangle represents the amount of space enclosed within its boundaries. It is calculated by multiplying the length by the width. The formula is:
Area = Length × Width
The unit of area is always in square units (e.g., square meters, square inches).

2. Perimeter

The perimeter of a rectangle is the total distance around its outer edges. It is calculated by adding the lengths of all four sides. Since opposite sides are equal, the formula simplifies to:
Perimeter = 2 × (Length + Width)
The unit of perimeter is in linear units (e.g., meters, inches).

3. Diagonal

The diagonal of a rectangle is the straight line connecting two opposite corners. It can be calculated using the Pythagorean theorem, as the diagonal forms the hypotenuse of a right triangle with the length and width as the other two sides. The formula is:
Diagonal = √(Length² + Width²)
The unit of the diagonal is the same as the linear units of length and width.