# Exploring Inscribed Angles

- Author:
- James McKee

## Instructions For Part 1

In the circle below, use the ray tool to create rays OB and OC, which creates a central angle. Use the angle measurement tool to measure . Then create rays AB and AC which creates an inscribed angle. Measure .

Now use the arrow tool tool to move around points A, B and/or C.

What do you notice is the relationship between the central angle () and the inscribed angle ()

## Instructions for Part 2

Use the ray tool to create rays AB, AC, DB and DC. Use the angle measurement tool to measure and .

You can use the arrow tool to move the points around on the circle. What do you notice always seems to be true about and ?

## Instructions for Part 3

On the circle below use the segment tool to create segments AB and AC. Use the angle measurement tool to measure angle CAB.

Use the arrow tool to move point A around on the circle. What do you notice is true about angle CAB?

Look back at your answer to Part 1. Explain why angle CAB *has to be* what it turned out to be.

So what kind of triangle is ABC?