MathVillage

 This page shows the different types of angles and their names: acute, right, obtuse, straight, and reflex.

We have found that there is a relationship between the number of sides of a polygon and the sum of its angles. What about a 5-pointed star?

Use this applet to investigate the sum of angles in polygons. Is there a pattern? Can you predict the sum of the angles in a 20-sided polygon?

This is the cover page for the Lines and Angles pages.

What are vertical angles? This applet shows you.

A different demonstration of why the sum of the angles in a triangle is always 180°.

What is the sum of the angles in ANY triangle?

What are supplementary angles? Use this applet to find out.

Practice using a protractor with this applet.

If two angles are supplements, find the missing angle.