Angles Formed by Radii, Chords, and Tangents.
READ the instructions on the right and INTERACT with the GeoGebra applet below.
|
|
|
|
Investigation Steps
Click on the 
icon to reset the diagram.
| Figure 1 Close |
- Move point C on the circle. What happens to the arc CI?
- What do you notice about the measure of the blue angle at point J? (See the formula as it changes values.)
- Move points D,H, and I to change the measure of the intercepted arcs.
- Notice the change in the angle measure each time.
|
| Figure 2 Close |
- Move point E to change the measure of the arc EF. What happens to the measure of the blue angle at point F?
- As the arc measure increases, what does the angle measure do?
- Move the point of tangency F (the tangent line will move with it). What happens to the blue angle as the arc measure increases or decreases?
|