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:

# Perimeter of a Pentagon

## The Perimeter Formulas

There are two formulas for finding perimeter of a pentagon.

For a regular pentagon where all sides are the same length, the formula is given as:**P = 5s**

Where *P* is the perimeter and *s* is the side length.

For an irregular pentagon where the sides are not all the same length, the formula is given as:**P = a + b + c + d + e**

Where *a* → *e* are the lengths of each side.

### Example Problems

Problem 1:

Find the perimeter of a regular pentagon with a side length of 15.

Solution:

Since we know this is a regular pentagon, we can plug the side length 15 into the regular pentagon formula.

P = 5s

P = 5(15) = 75**The perimeter is 75.**

Problem 2:

In irregular pentagon has side lengths a = 2.36, b = 4.01, c = 3.12, d = 3.22, and e = 4.41. What is the perimeter?

Solution:

Let’s plug the side lengths into the irregular pentagon formula.

P = a + b + c + d + e

P = 2.36 + 4.01 + 3.12 + 3.22 + 4.41 = 17.12**The perimeter is 17.12.**