Table of contents  
What is Mensuration?  
Perimeter  
Area  
Summary 
Mensuration is a branch of mathematics that is a topic in Geometry. It is a study of various geometrical shapes, their length, breadth, volume, and area for 2D as well as 3D shapes.
Some important terminologies included in this topic are covered below.
Perimeter is the distance covered along the boundary forming a closed figure when we go around the figure once. The concept of the perimeter is widely used in real life. For Example:
= 2 (l + b)
Example 1: A rectangle has a length of 5 units and a breadth of 3 units.
Solution:
Perimeter = 2(length + breadth)
= 2(5 + 3)
= 2(8)= 16 units
Example 2: A rectangular garden has a length of 15 meters and a breadth of 7 meters. Find the perimeter of the garden.
The perimeter of a rectangle is given by the formula P = 2(l + b), where l is the length and b is the breadth.
l = 15 meters
b = 7 meters
So, the perimeter is P = 2(15 + 7)
= 2(22)= 44 meters
= 4 x S
Example 1: A square has a side length of 4 units.
Perimeter = 4 * side
length = 4 * 4= 16 units
Example 2: A square photo frame has a side length of 8 centimeters. Find the perimeter of the photo frame.
The perimeter of a square is given by the formula P = 4s, where s is the side length.
s = 8 centimeters
So, the perimeter is P = 4(8)
= 32 centimeters
The perimeter of an equilateral triangle with the side 'a'=a+a+a =3 x a
Example 1: An equilateral triangle has a side length of 6 units.
Perimeter = 3 * side length
= 3 * 6
= 18 units
Example 2: An equilateral triangle has a side length of 10 inches. Find the perimeter of the triangle.
The perimeter of an equilateral triangle is given by the formula P = 3s, where s is the side length.
s = 10 inches
So, the perimeter is P = 3(10)= 30 inches
The amount of surface enclosed by a closed figure is called its area. The following conventions are to be adopted while calculating the area of a closed figure using a squared or graph paper.
For example, the area of this shape can be calculated as shown:
The area of the rectangle can be obtained by multiplying the length by the breadth.
Area = length ( l ) × breadth ( b)
Example: Find the area of a rectangle with a length 8 units and breadth 5 units.
The formula for the area of a rectangle is
A = length × breadth
A = 8 × 5
A = 40 square units
The area of the square can be obtained by multiplying side by side.
Area of a square = Side × Side =Side2=a2, where a is the length of each side.
Example: Find the area of a square with a side length of 6 units.
The formula for the area of a square is
A = side × side
A = 6 × 6
A = 36 square units
Area of triangle = (1/2) × base × height = (1/2) × b × h
Example: Find the area of a triangle with a base of 10 units and height of 4 units.
The formula for the area of a triangle is
A = (1/2) × base × height.
A = (1/2) × 10 × 4
A = 20 square units
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1. What is the formula for finding the perimeter of a rectangle? 
2. How can the area of a triangle be calculated? 
3. What is the difference between perimeter and area? 
4. How can the area of a circle be calculated? 
5. What is the formula for finding the perimeter of a circle? 

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