Copy of Angles Outside the Circle
Angles formed by Secant Lines
Secant lines intersect a circle at two points.
Activity Directions: Move points D, C, B, and E to discover the relationship between the measure of the angle created by two secant lines and the measures of the intercepted arcs.
Which is true about the two segments you see?
What happens if you add arc CB and arc DE?
What happens in you subtract arc CB from arc DE?
You should notice that there is a relationship between the angle and the difference in the two arcs.
What happens if you double the measure of the angle?
If you were going to write this relationship as a formula, what would it be?