Obtuse Angles
(KS2, Year 6)

An obtuse angle is an angle greater than 90° and less than 180°.

An obtuse angle is greater than a right angle and less than a straight line.

Dictionary Definition

The Oxford English Dictionary defines an obtuse angle as "a plane angle: greater than 90 degrees and less than 180 degrees."

The angles below are all obtuse angles:

example of obtuse angles. 135, 160 and 91 degrees.

Here is an interactive game to help you learn about the types of angles.

Click on an angle so it drops into the correct "bucket."
In total, there are 10 angles to clear.
If an angle drops into the wrong "bucket," you will lose one of your three lives.
Good luck!

Obtuse comes from the Latin word "obtusus" meaning "blunt". An obtuse angle makes a blunt point.

Euclid defines angles in his book, Elements. Definition 11: "An obtuse angle is an angle greater than a right angle".

Obtuse triangles are triangles that have an obtuse angle.

an obtuse triangle

Here is a drag-and-drop game to help you learn about the types of angles.

This page was written by Stephen Clarke.