This document defines different types of angles and their measurements in degrees. It explains that angles are a measure of the amount of turn between two lines sharing a common endpoint, called the vertex. The types of angles are acute (less than 90 degrees), right (90 degrees), obtuse (between 90 and 180 degrees), straight (180 degrees), and reflex (greater than 180 degrees). A full rotation is 360 degrees.

1. Review of Angles
90˚ 180˚ 270˚ 360˚
Angles are a measure of the amount, or degree of turning from one
line to another around a common point, called the vertex.
degree
vertex
Quarter Turn Half-Turn
Three-Quarter Turn Full-Turn
REMEMBER: a right angle is 90˚.

2. Important Vocabulary
90˚
Copy the above angle and vocabulary into your notebook.
Degree (a measure
for angles)
Vertex
(an endpoint
where two
line segments
or lines come
together)
90˚ = Right Angle

3. Types of Angles

4. Types of Angles
Type of Angle Description
Acute Angle An angle that is less than 90˚
Right Angle An angle that is exactly 90˚
Obtuse Angle An angle that is greater than 90˚ but less than 180˚
Straight Angle An angle that is 180˚ exactly
Reflex Angle An angle that is greater than 180˚
Full Rotation 360˚
Copy the chart above into your notebook.