The **perimeter of a triangle** is defined as the total length of its boundary. A triangle is a polygon with 3 sides and it can be classified into different types based on the measure of its sides and angles. There are different formulas and methods to calculate the perimeter of a triangle based on the type of triangle.

**Perimeter = Sum of the three sides**

Always include units in the final answer. If the sides of the triangle are measured in centimeters, then the final answer should also be in centimeters.

### The Perimeter of Triangle Formula

The formula for the perimeter of a closed shape figure is usually equal to the length of the outer line of the figure. Therefore, in the case of a triangle, It will be the sum of all the three sides. If a triangle has three sides a, b and c, then,

**P = a + b +c**

#### Perimeter of Right Triangle

A right triangle has a base(b), hypotenuse(h) and perpendicular(p) as its sides, By the Pythagoras theorem, we know,

h^{2} = b^{2} + p^{2}

Therefore, the Perimeter of a right angle triangle= b + p + h

**Ex 1:****Calculate the Perimeter of a Right Triangle with a Base of 3 cm and a height of 4 cm.**

First, using the Pythagorean theorem, calculate the hypotenuse of the right triangle.

hypotenuse =√(base^{2}+perpendicular^{2})

h = √(3^{2}+4^{2})

h = √(9 + 16)

hypotenuse = √25

Or, h = 5 cm

So, P = 3 + 4 + 5 = 12 cm.

**Example 2:****Find the perimeter of a polygon whose sides are 5 cm, 4 cm and 2 cm.**

**Solution**: Let,

a = 5 cm

b = 4 cm

c = 2 cm

**P** = Sum of all sides = a + b + c = 5 + 4 + 2 = 11

Therefore, the answer is 11 cm.

**Example 3**:**Find the perimeter of a triangle whose each side is 10 cm.**

**Solution**: Since all three sides are equal in length, the triangle is equilateral.

i.e. a = b = c = 10 cm

P = a + b + c

= 10 + 10 + 10

= 30

P = 30 cm.