# Angle Bisectors of a Triangle

- Author:
- Jill Alsman, Rachel Fruin

Discover properties of angle bisectors

Part 1
1. BD is an angle bisector of angle ABC. Drag point C around. Write a definition for angle bisector based on your observations.
2. Drag points A and B around. Does your definition from #1 hold true?
3. Click: Show segments from angle bisector
4. Drag point D, what can you conclude about points on the angle bisector?
Part 2
5. Click: Show Segment AC and Show 2nd Angle Bisector
6. Are the properties you found of angle bisector Line BD also true of angle bisector Line CG?
Part 3
7. Click: Show 3rd Angle Bisector
8. What do you notice about the 3 angle bisectors?
9. Drag the 3 vertices of the triangle (A, B and C). Do the angle bisectors always intersect? Do they ever intersect outside of the triangle?
10. Drag points D and G to the intersection of the 3 angle bisectors. What do you notice about the 3 segments perpendicular to the sides of the triangle?
Write a conclusion about what you learned through this lab.