Types of Angles Based on Measurement

There are six types of angles on the basis of measurement. They are:

• Acute Angle
• Right Angle 
• Obtuse Angle
• Straight Angle
• Reflex Angle
• Complete Angle

Learn More, 7 Types of Angles

Acute Angle

The angle that measures less than 90° is the Acute Angle. The degree always measures between 0 and 90. Acute angles measure positive when the rotation is anticlockwise and negative when the rotation of the angle is clockwise.

In the figure, O is the vertex of the angle, and OA and OB are two intersecting rays that meet at point O forming an angle less than 90°. Hence, ∠AOB is an acute angle.

Right Angle

The angle that exactly measures 90° is called a Right Angle. It is also considered as a half straight angle as half of 180° makes a right angle. The value of the angle may be positive or negative on the basis of the rotation of the angle.

In the figure, O is the vertex of the angle, and OA and OB are two intersecting rays that meet at point O forming an angle of exactly 90°. Hence, ∠AOB is a right angle. Also when two rays meet to form a 90° angle there are called Perpendicular to each other. Here OA and OB are perpendicular to each other.

Obtuse Angle

The angle that measures more than 90° and less than 180° is called an Obtuse Angle. The degree always lies between 90° and 180°. The value of the obtuse angle will be positive if the rotation is anticlockwise and negative if the rotation is clockwise.

In the figure, O is the vertex of the angle, and OA and OB are two intersecting rays that meet at point O forming an angle of more than 90°. Hence, ∠AOB is an obtuse angle.

Straight Angle

The angle that measures exactly 180° is a Straight Angle. It is called Straight Angle because when two rays make 180° between them then they are in a straight line.

In the figure, of a straight angle, we can observe that O is the meeting point of two arms, called the vertex and OA and OB are two sides of the angle.

Reflex Angle

The angle that measures more than 180° and less than 360° is called a Reflex Angle. The degree always lies between 180° and 360°.

In the figure, O is the vertex of the angle, and OA and OB are two intersecting rays that meet at point O forming an angle of more than 180°. Hence, ∠AOB is a reflex angle.

Complete Angle

The angle whose measurement is 360° is called a Complete Angle. It happens when you make a complete turnaround and reach the initial point then in this case the angle is Complete Angle. 

Let’s now study angle on the basis of Rotation

An angle is a figure which is formed by two rays or lines that share a common endpoint is called an angle. The word “angle” is derived from the Latin word “angulus”, which means “corner”. The two lines joined together are called the arms of the angle and the measure of the opening between them is the value of the angle between these two lines.

In this article, we will learn about the definition and parts of angles in Geometry, their representation, examples, and types like acute angle, right angle, obtuse angle, etc. along with FAQs.