Angle Bisector – a line, segment, or ray that bisects an angle Incenter – the point of concurrency where the three angle bisectors of a triangle intersect Construct an incenter 1.) To find Geometer’s Sketchpad -­‐ click the magnifying glass in the top right corner of the screen and search for: GSP (click on the top hit – the yellow diamond with the shapes) 2.) Click the segment button
on the toolbar. 3.) Click to make a line segment. Start another line segment at one of the end points (the point will become outlined in red when you are on the point) 4.) Click to make a third line segment closing the triangle. 5.) Click the cursor button on the toolbar and click in the white space to deselect all points and segments. 6.) Click on each of the vertices of your triangle in a clockwise rotation and choose Construct > Angle Bisector. Deselect all points and segments. 7.) Start on a different vertex and click on each of the vertices of your triangle in a clockwise rotation and choose Construct > Angle Bisector. Deselect all points and segments. 8.) Start on your third and final vertex and click on each of the vertices of your triangle in a clockwise rotation and choose Construct > Angle Bisector. Deselect all points and segments. 9.) Highlight two of your angle bisectors and choose Construct > Intersection. The point you just constructed is your incenter. Deselect all points and segments. 10.)Click the circle button on the toolbar. Click on your incenter to center your circle there. Stretch the circle so that it intersects each side of your triangle.