Think about what the word "bisect" means. What do you think an angle bisector would look like? What would happen to an angle if it was bisected? Play with the applet below and then answer questions #1-4 at the bottom of the page.

1) Move the slider so that angle ABD( )= 80 degrees. What do you notice about angle ABC and angle CBD?
2) Move the slider so that angle ABD ( )= 161 degrees. What do you notice about angle ABC and angle CBD?
3) Move the slider to a degree measure of your choosing. What do you notice about angle ABC and angle CBD?
4) Line BC is called an angle bisector. Using your information from questions 1-3, what is your best definition for "angle bisector"?