1. Education
Send to a Friend via Email
Geometry Course
Types of Angles - Part 2
Free Geometry Basics Course
Part 1
 Terms in Geometry
Part 2
 Types of Angles
Part 3
Part 4
Measuring Angles
Part 5
Bisectors, Congruencies, Theorems
Part 6
Transfersal Properties
Geometry Help
• Mathematicians Review
Conic Sections
• Pythagorean Theorem

 Related Resources
Measurement Formulas
Recommended Resources
Area Calculator
Introduction to Polygons


An angle is defined as: where two rays or two line segments join at a common endpoint called the vertex. See part 1 for additional information.

Acute Angle

An acute angle measures less that 90° and can look something like these (angles between the grey rays):

Right Angle

A right angle measures exactly 90° and will look something like this:

Obtuse Angle

An obtuse angle measures more than 90° but less than 180° and will look something like these:

Straight Angle

A straight angle is 180°

Reflex Angle

An reflex angle is more than 180° but less than 360° and will look something like this:

Pairs of Angles:

Complementary Angles
Two angles adding up to 90° are called complementary angles.

ABD + DBC are Complementary

Supplementary Angles
Two angles adding up to 180° are called supplementary angles.

ABD + DBC are Supplementary

If you know the angle of ABD, you can easily determine what the DBC is by subtracting ABD from 180!

On to Part 3.

Previous Articles

You can opt-out at any time. Please refer to our privacy policy for contact information.

Discuss in my forum

See More About

©2014 About.com. All rights reserved.