Geometry

##### Related Lessons

- 3 4 5 Triangle
- 30 60 90 Triangle
- 45 45 90 Triangle
- 5 12 13 Triangle
- Arc Length Calculator
- Area of a Circle Calculator
- Area of a Hexagon
- Area of a Kite
- Area of a Parallelogram
- Area of a Pentagon
- Area of a Rectangle
- Area of a Rhombus
- Area of a Sector
- Area of a Semicircle
- Area of a Square
- Area of a Trapezoid
- Area of a Triangle
- Center of Mass Calculator
- Circumference Calculator
- Distance Formula
- Distance Formula Calculator
- Geometry Calculators
- How to Find the Height of a Triangle
- Isosceles Triangle Theorem
- Law of Cosines Calculator
- Perimeter of a Circle
- Perimeter of a Pentagon
- Perimeter of a Rectangle
- Perimeter of a Rhombus
- Perimeter of a Semicircle
- Perimeter of a Square
- Perimeter of a Trapezoid
- Perimeter of a Triangle
- Properties of a Parallelogram
- Pythagorean Theorem Calculator
- Side Angle Side Theorem
- Side Splitter Theorem
- Similar Triangles
- Special Right Triangles
- Surface Area of a Cone
- Surface Area of a Cube
- Surface Area of a Cylinder
- Surface Area of a Hemisphere
- Surface Area of a Pyramid
- Surface Area of a Sphere
- Surface Area of a Triangular Prism
- Triangle Inequality Theorem
- Types of Triangles
- Vertical Angles
- Volume of a Cone
- Volume of a Cube
- Volume of a Hexagonal Prism
- Volume of a Pyramid
- Volume of a Sphere
- Volume of Hemisphere
- Volume of Parallelepiped

Tutors/teachers:

Nikkolas

Tutor and Aerospace Engineer

# Perimeter of a Triangle

## 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.

### Example Problems

**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.**

**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.**

Result :

Worksheet 1

Download.pdf

Cheat sheet

Download.pdf