**Closed figure:**A figure with **no open ends** is a closed figure.

Regular closed figures: A closed figure in which **all the sides** and **angles equal.**

#### Perimeter:

Perimeter is the distance covered along the boundary forming a closed figure when we go round the figure once. The concept of perimeter is widely used in real life.Eg: 1) For fencing land.

2) For building a compound wall around a house.

The perimeter of a regular closed figure is equal to the sum of its sides.

#### Perimeter of a rectangle:

#### Perimeter of a square:

#### Equilateral triangle:

A triangle with **all its sides and angles equal** is called an equilateral triangle.

The perimeter of an equilateral triangle with the side 'a'