## Types of angles

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

## Angles in a star

# What is the sum of the angles in a star?

For this investigation, create *several* different five-pointed stars. Then measure the internal angles of the five points. Record your measurements in a table. **Use words, numbers, and pictures to clearly explain your findings.**

Examples of stars:

## Angles in Polygons

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?

Use the applet...

## Why is the sum always 180°? (A different look.)

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

## Supplementary Angles - the definition

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

## Supplementary Angles - find the missing angle

If two angles are supplements, find the missing angle.