Open the file tm7.6.gsp by clicking here
Follow these steps:
1. Move the points around to see what you can do with this diagram.
2. Notice there are 5 points. Label each of them by clicking on the Label tool and pointing to each point.
3. Measure Angle ACB. Highlight point A. Hold the shift key down and click on C. Continue holding and click on D. Go to measure and click on angle. You should see the measure of angle ACB. Note the vertex of the angle is always in the middle!
4. Repeat step 3 for Angle BCE.
5. Move point D around. What do you notice about angles ACB and BCE?
6. Repeat for the other two angles.
7. What do you notice about those angles when you move point D around?
8. Is it possible for all four angles to be equal? What is the angle measure of the angles?
9. What angles add up to 180 degrees? What are these angles called?