Perimeter of a triangle — lesson. Mathematics CBSE, Class 6.

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Now, we shall find the perimeter of an equilateral triangle.

Let

$ABC$ be an equilateral triangle with sides of equal length

$s$

$units$ .

Then, the perimeter of the triangle

$ABC$ is given by:

Perimeter of the triangle

$=$ Product of

$3$ sides and its side length

Perimeter

$P = AB+BC+CA$

$units$

$P = s+s+s$

$units$

$P = 3s$

$units$

Therefore, the perimeter of an equilateral triangle is the product of

$3$ sides and the side length.

Example:

1. The side length of an equilateral triangle is

$9 \ cm$ . Find the perimeter of an equilateral triangle.

Solution:

The side length of an equilateral triangle is

$s = 9$

$cm$ .

Perimeter

$= 3s$ , where

$s$ is the length of three equal sides.

Substituting the value of

$s$ in the above formula, we have:

Perimeter

$= 3 \times 9$

$cm$

Perimeter

$= 27$

$cm$

Therefore, the perimeter of an equilateral triangle is

$27 \ cm$ .

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4. Perimeter of a triangle

Theory: