1. If the vertex angle is the center of the circle(point A), how do we know this must be an isosceles triangle?
2. Use the [icon]/images/ggb/toolbar/mode_angle.png[/icon] to measure the base angles. What can you say about their measures?
3. Drag points B and C. What can you say about the measures of the base angles?
4. Click this [icon]/images/ggb/toolbar/mode_linebisector.png[/icon]and slide down to this icon [icon]/images/ggb/toolbar/mode_angularbisector.png[/icon] to bisect vertex angle A. What can you say about the two triangles that are generated? Why?