**Interior and Exterior of an Angle:** Let us start our article by knowing what is an angle? We know that an angle is a space between two intersecting lines. The angles are measured in degrees. The measure of an angle is denoted by °. There are different types of angles. One is an interior angle and the other is an exterior angle.

A detailed explanation of the Interior and Exterior of an Angle is given on this page. Thus the students of 5th grade are suggested to check out the problems on interior and exterior angles and test their knowledge of geometry.

**Do Refer related articles:**

## Interior and Exterior of an Angle – Definition

**Definition of Interior Angle:-** The part of a plane that is within the arms of an angle is called the interior of an angle. In an interior angle, the angle is formed inside the polygon.

**Definition of Exterior Angle:-** The part of a plane that is outside the arms of an angle is called the exterior of an angle. In an exterior angle, the angle is formed outside the polygon by extending the intersection point.

### Interior Vs. Exterior Angles

An angle that is inside of a shape is known as the interior of an angle. An angle that is outside of a shape is known as the exterior of an angle. By seeing the above figure we can find the difference between the interior and exterior angles of a polygon. An exterior angle is formed by extending the lines a shape beyond the point of intersection. It is very important to know about exterior and interior angles in any polygon. This helps you to measure the angles in a shape.

### Interior and Exterior of an Angle Examples

**Example 1.**

**Solution:**

In the above diagram, ∠ACB is the interior angle because it is within the arms and the extended point ∠ACX is the exterior angle because it is outside the arms.

**Example 2.**

**Solution:**

In the above diagram, ∠BAC is the interior angle because it is within the arms and the extended point ∠ACO is the exterior angle because it is outside the arms.

**Example 3.**

**Solution:**

In the above diagram, ∠XOY is the interior angle because it is within the arms.

**Example 4.**

**Solution:**

In the above diagram, ∠MON is the interior angle because it is within the arms and the extended point ∠MNY is the exterior angle because it is outside the arms.

**Example 5.**

**Solution:**

In the above diagram, ∠XOY is the interior angle because it is within the arms and the extended point ∠XYO is the exterior angle because it is outside the arms.

### FAQs on Interior and Exterior of an Angle

**1. What is the interior of an angle?**

Any angle that is inside the shape is called an interior angle.

**2. What is the exterior of an angle?**

Any angle that is outside of a shape is called an exterior angle.

**3. How do you find the interior and exterior angles?**

The formula for calculating the size of an interior angle is the interior angle of a polygon = sum of interior angles ÷ the number of sides.

The formula for calculating the size of an exterior angle is the exterior angle of a polygon = 360 ÷ number of sides.