Angle Bisectors

Jill Casey

You will be constructing 3 angle bisectors in one triangle.


1. Select the triangle tool and create an acute, scalene triangle. Make sure to select the pointer tool afterwards in order to not keep creating polygons! 2. Select the point and line tool (4th from the left) and choose angle bisector from the drop down menu. The directions on how to select the items in order to create an angle bisector will appear at the bottom of the screen. (Select three points or two segments.) 3. You will do this two more times to create three angle bisectors.

What do you notice about the three angle bisectors?

This point is special! You will discover why. Step 1: Choose the circle tool and circle with center through a point. Step 2: Click on the intersection of the angle bisectors to make that point the center of a circle. Step 3: Drag the circle until you can click on one of the sides of the triangle.

What do you notice about this circle?