# Constructing Angle Bisectors

- Author:
- Bob Allen

An angle bisector is a ray that has its endpoint at the vertex of the angle and divcides the angle into two angles of equal measure. In this investigation, you'll investigate a special property of points on an angle bisector.

Please read the following instructions carefully.
1. Use the Ray tool to draw ray

*AB*and ray*AC*. Remember to label your points. 2. Use the Angle Bisector Tool then click either the two rays or points*C*,*A*,*B*in that order. Or is it*B, A, C*? 3. Construct a point*D*on the angle bisector with the Point on Object tool. 4. Use the Distance or Length tool to measure from point*D*to ray*AB*. 5. Use the Distace or Length tool to measure from point*D*to ray*AC*.To confirm that ray *AD* bisects angle* BAC*, measure angles *BAD* and *DAC.* (If the correct angle doesn't show up, reverse the order you're clicking the points.) Drag points *A*, *B*, and *C* to change angle *BAC*. How do the angle measures compare?

Drag point *D* and observe the distances from point *D* to the two sides of the angle. Write a conjecture about any point on the bisector of an angle. Hint: The if part should include point D and the angle bisector and the then part should include the measurements from D to the angle.

Did you actually read the instructions this time?