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:
A triangle with all its sides and angles equal is called an equilateral triangle.
The perimeter of an equilateral triangle with the side 'a'