 # What are the Different Angle Pairs?

## What is an Angle?

When two rays share a common endpoint, the geometric figure created is called an angle. The rays or lines that intersect or join at a common point to form the angle are called the sides of that angle. The units used for measuring angles are degrees or radians. If two angles are displayed together to represent some geometrical property, it is referred to as angle pairs. In Mathematics, there are several angle pairs such as complementary angles, supplementary angles, adjacent angles, etc. In this article, we will learn more about all the available angle pairs.

## Pairs of Angles

### Complementary Angles

If the sum of two angles adds up to give 90 degrees, such a pair of angles is known as complementary angles. For example, 400 and 500 are complementary angles because 400 + 500 = 900. If we have two right angles, they cannot complement each other. Similarly, two obtuse angles do not complement each other. Any two complementary angles are always acute.

### Supplementary Angles

If the sum of two angles adds up to give 180 degrees or a straight line, such a pair of angles is known as supplementary angles. For example, 600 and 1200 are supplementary angles because 600 + 1200 = 1800.

### Vertically Opposite Angles

When two lines intersect, the pair of angles so formed is known as vertically opposite angles. These angles are opposite to each other. These vertical angles are equal in measure. Suppose we have two intersecting lines forming angles A, B, C, and D. A and C will form one pair of vertical angles that are equal to each other, while B and D will form the other vertical pair.

### Alternate Interior Angles

When a line intersects two parallel lines, the pair of angles so formed are known as alternate interior angles. These angles are always equal to each other.

### Alternate Exterior Angles

When a line intersects two parallel lines, the vertically opposite angles of the alternate interior angles are known as the alternate exterior angles. These angles are equivalent to each other.

### Corresponding Angles

The pairs of angles that get formed when a line intersects two parallel lines are known as corresponding angles. These pairs of corresponding angles are also equal to each other.