# Octagon Shape – Definition, Properties, Formula

The world of geometry is a treasure trove of shapes and figures, each with its unique properties and characteristics. Among these, the octagon stands as a captivating eight-sided polygon with intriguing properties and a rich history.

An octagon is an eight-sided polygon, a 2D shape with eight straight sides and eight angles. The term “octagon” is derived from the Greek words “octo,” meaning “eight,” and “gonia,” meaning “angle.” Octagons are known for their symmetry and unique visual appeal.

In this comprehensive guide, we will delve deep into the realm of octagons, exploring their definition, types, properties, real-world examples, and even provide a tutorial on how to draw and work with octagons in various contexts.

1. What is an Octagon?
2. Types of Octagons
3. Properties of Octagons
4. Real-World Octagon Examples
5. Perimeter of an Octagon
6. Area of Regular Octagon
7. Solved Examples on Octagon
8. Octagon FAQs

## What is an Octagon?

An octagon is a polygon with eight sides and eight angles. The term “octagon” is derived from the Greek words “octo,” meaning “eight,” and “gonia,” meaning “angle.” Octagons can come in various forms, including regular octagons (with all sides and angles equal) and irregular octagons (with varying side lengths and angles).

In a regular octagon, each interior angle measures 135 degrees, and all sides are of equal length. The sum of the interior angles of an octagon is always 1080 degrees. Octagons are known for their symmetrical and balanced appearance, and they find applications in various fields, including mathematics, design, and architecture. ## Types of Octagons

Octagons come in various forms:

• Regular Octagon: All eight sides and angles are equal in length and measure, creating a symmetrical polygon.
• Irregular Octagon: Side lengths and angles may vary, leading to a lack of overall symmetry.
• Convex Octagon: All interior angles are less than 180 degrees, giving the shape an outward bulge.
• Concave Octagon: At least one interior angle is greater than 180 degrees, resulting in a “caved-in” appearance. ## Properties of Octagons

Octagons exhibit distinct properties:

• Eight Sides: Every octagon has eight straight sides.
• Eight Angles: Octagons possess eight interior angles.
• Sum of Angles: The sum of the interior angles in an octagon is always 1080 degrees.
• Diagonals: An octagon has 20 diagonals connecting non-adjacent vertices.

### Real-World Octagon Examples

Octagons are not just mathematical constructs; they find practical applications:

• Stop Signs: The classic red stop sign is a real-world octagon, conveying the importance of stopping at intersections.
• Octagonal Tiling: In interior design and architecture, octagonal tiles are used to create visually appealing patterns.
• Stop Octagonal Nuts: These specialized nuts are used in engineering for secure fastening in various industries. ## Perimeter of an Octagon

The perimeter of an octagon, which is the total length of its eight sides, depends on the lengths of those sides. If you know the lengths of all eight sides, you can find the perimeter by simply adding them together:

Perimeter= Side1+Side2+Side3+Side4+Side5+Side6+Side7+Side8
Where “Side_1,” “Side_2,” and so on represent the lengths of the eight sides of the octagon.

For a regular octagon (where all sides are equal), you can simplify the calculation by multiplying the side length (s) by 8:

Perimeter of a Regular Octagon = 8 × Side

For an irregular octagon (where side lengths may vary), you need to sum the lengths of all eight sides to find the perimeter.

## Area of Regular Octagon

To calculate the area of a regular octagon, where all sides and angles are equal, you can use the following formula:

OR

Area = 2(Side)2(1 + √2)

Where:

“Side” is the length of one side of the regular octagon.

By using this formula, you can find the area of a regular octagon when you know the length of one of its sides.

## Solved Examples on Octagon

Problem 1 – Find the perimeter of a regular octagon with a side length of 6 meters.

Solution: For a regular octagon, you can use the formula to find its perimeter:

Perimeter=8×Side

Substitute the side length (Side = 6 meters) into the formula:

Perimeter= 8 × 6meters= 48meters

So, the perimeter of the regular octagon is 48 meters.

Problem 2- If the side length of a regular octagon is 7 cm. Find its area.

Solution:

Given, length of the side of the octagon, a = 7 cm

Area = 2a2(1+√2) = 2 (7)2(1+√2) =  236.6 sq.cm.

Q1: What is an octagon?

A1: An octagon is a polygon with eight sides and eight angles. It can come in various forms, including regular (with all sides and angles equal) and irregular (with varying side lengths and angles).

Q2: What is the sum of interior angles in an octagon?

A2: The sum of interior angles in an octagon is always 1080 degrees.

Q3: How do you calculate the area of a regular octagon?

A3: You can use the formula: Area =  2(Side)2 × tan(π/8), where “Side” is the length of one side of the regular octagon.

###### Q4: How many diagonals does an octagon have?

A4: An octagon has 20 diagonals, which are line segments connecting non-adjacent vertices of the octagon.

Q5: What are some real-world examples of octagons?

A5: Octagons are commonly seen in everyday life, such as in stop signs, certain architectural designs, and decorative tiling patterns.

Q6: Are there different types of octagons?

A6: Yes, octagons can be categorized as regular or irregular, convex, or concave based on their symmetry and angle measurements.