## Perimeter of a Triangle Lesson

### The Perimeter Formula

A triangle is a polygon with three sides and three vertices. The formula for perimeter is given as:

**P = a + b + c**

Where *P* is the perimeter, and *a*, *b*, and *c* are the three side lengths.

INTRODUCING

### Perimeter of a Triangle Example Problems

Let's go through a couple of example problems to practice finding the perimeter of a triangle.

#### Example Problem 1

What is the perimeter of a triangle with side lengths of 5, 6, and 3?

Solution:

- Let’s plug the side lengths into the perimeter formula.
- P = a + b + c
- P = 5 + 6 + 3 = 14
**The perimeter of the triangle is 14.**

#### Example Problem 2

An equilateral triangle has a perimeter measured to be 81 centimeters. What are the side lengths?

Solution:

- Since an equilateral triangle has three equal sides, a = b = c. We can substitute a + b + c with 3a.
- Plugging what we know into the perimeter formula, we get:

P = a + b + c

81 = 3a

a = 27, b = 27, c = 27 **The three sides each have a length of 27 centimeters.**