Exterior
Angles of a Circle
Jenni McIntire and Teresa Davis
This lab is to investigate the measure of an angle on the exterior of
a circle.
Investigation:
In Sketchpad,, make the following construction.
- Construct circle A.
- Construct points C, D, E, and F on the circle in consecutive order.
- Construct secants CD and EF and have them intersect outside the circle
at point G.
- Measure angle CGF and its two intercepted arcs DE and CF.
Try adding, subtracting, multiplying, and dividing to find a relationship
between the angle and its intercepted arcs.
Write a formula for the measure of an exterior angle of a circle in relationship
to the intercepted arcs.
Exterior Angle = ___________________
Fill in the chart:
Vertex of Angle Angle Measure
| On the Center |
Angle = _______________ |
| On the Circle |
Angle = _______________ |
| Interior of Circle |
Angle = _______________ |
| Exterior of Circle |
Angle = _______________ |
Check chart with your teacher before starting the exercises.
Exercises:
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