There are two types of geometry: 2D Geometry and 3D Geometry. They are all composed of points, lines, rays, and plane surfaces before classification. **Angles are measurements between two lines or rays convergent at the same point.**

## What are Angles?

An angle is formed by the combination of two rays with a common endpoint. An angle consists of two components, the sides, and the vertex. Sides can be classified as terminal sides (or vertical sides) or initial sides (or horizontal sides).

### Parts of Angle

- Vertex – The intersection of two arms.
- Arms – A vertex is formed by two straight lines.
- Angle – The angle between the initial and final position of a ray is defined by the rotation it undergoes at its endpoint.

**Kindes of Angle**

There are two Kindes of angles

- Positive Angle
- Negative Angle

**Positive Angle**

Positive angles are those that go counterclockwise.

**Negative Angle**

Negative angles are those that go clockwise.

**Types of Angle**

**Acute Angle**

An angle measure less than 90 degrees.

**Right Angle**

An angle is exactly 90 degrees.

**Obtuse Angle**

An angle whose measure is greater than 90 degrees and less than 180 degrees.

**Straight Angle**

An angle that is exactly 180 degrees.

**Reflex Angle**

An angle whose measure is greater than 180 degrees and less than 360 degrees.

**Full Angle**

An angle whose measure is exactly at 360 degrees.

**Other Types of Angles**

Angles are also sometimes classified based on their position, the direction of rotation, the sum of their pairs, or their transversal into the following types:

**Interior Angles****Exterior Angles****Positive Angles****Negative Angles****Complementary Angles****Supplementary Angles****Vertically Opposite Angles****Adjacent Angles****Alternate Interior Angles****Alternate Exterior Angles****Corresponding Angles****Consecutive interior Angles**

**Interior Angles**

## Inside angles are those located inside a shape.

**Exterior Angles**

## Exterior angles refer to those formed on the external surfaces of the shape.

**Complementary Angles**

Complementary angles are formed when the sum of two angles equals 90°. It is not necessary for the two angles to be equal in size in order to add up to 90°. For example, the two angles can be 45° and 45°.

**Supplementary Angles**

The sum of two angles is equal to 180°, they are called supplementary. The two angles when added make up 180°. For example, 110° and 70° make up 180°.