Angles – Definition, Parts, Types, FAQs, Examples

An angle can be defined as a shape created by two rays that share a terminus and are referred to as an angle's sides and vertices, respectively, Angels created by two rays are always located in the plane where the rays are located. The meeting of two planes also creates angles.

Parts Of Angles

An angle is formed by intersecting two straight lines at a point. It has the following parts:

1. Arms: It is the straight lines that are connected forming angles.

2. Vertex: An angle’s corner point is referred to as a vertex. It is the intersection point of the rays.

3. Initial side: It is also referred to as a reference line. It is used as a reference for all measurements.

4. Terminal side: The side up to which the angle measurement is to be made.

Types Of Angles

There are six types of angles:

1. Acute angle: The angle whose measurement is less than 90 degrees but more than 0 degrees is termed an acute angle.

2. Right Angle: The angle whose measurement is exactly equal to 90 degrees is termed as the right angle.

3. Obtuse Angle: The angle whose measurement is more than 90 degrees but less than 180 degrees is termed an Obtuse Angle.

4. Straight Angle: The angle whose measurement is exactly equal to 180 degrees is termed a straight angle.

5. Reflex Angle: The angle whose measurement is more than 180 degrees but less than 360 degrees is termed a Reflex Angle.

6. Full Angle: The angle whose measurement is exactly equal to 360 degrees is termed a full angle.

Interior Angle And Exterior Angle

• Interior angle: All the angles that are inside a polygon or the other closed object with the sides and angles are called interior angles.

• Exterior Angle: All the angles that are formed outside of the polygon are exterior angles. These are created between any side and a line that extends from the adjacent side.

Positive Angle And Negative Angle

The direction of the ray’s rotation determines whether the angles are positive or negative. The ray moves either in an anticlockwise or clockwise manner, resulting in the formation of positive or negative angles.

• Positive Angle: If the ray rotates anti-clockwise on a plane, the angle created as a result of the rotation is referred to as a positive angle.

• Negative Angle: On the other hand, if the ray rotates clockwise on a plane, the angle created as a result of the rotation is referred to as a negative angle.