Incenter Construction: With Angle Bisector Tool
DIRECTIONS:
1) Use the ANGLE BISECTOR 
tool to construct the 3 angle bisectors of the triangle.
2) Use the INTERSECT 
tool to plot the point of concurrency (incenter) of these 3 angle bisectors.
3) Go to the STEPS window.
Hide the 3 angle bisectors of this triangle (you've just constructed in step 1).
4) Use the PERPENDICULAR LINE 
tool to construct a line that passes through the incenter and is perpendicular to .
Further directions appear below the applet.
tool to construct the 3 angle bisectors of the triangle.
2) Use the INTERSECT tool to plot the point of concurrency (incenter) of these 3 angle bisectors.
3) Go to the STEPS window.
Hide the 3 angle bisectors of this triangle (you've just constructed in step 1).
4) Use the PERPENDICULAR LINE tool to construct a line that passes through the incenter and is perpendicular to .
Further directions appear below the applet. 5) Use the PERPENDICULAR LINE tool to construct a line that passes through the incenter and is perpendicular to .
6) Use the PERPENDICULAR LINE tool to construct a line that passes through the incenter and is perpendicular to .
7) Use the INTERSECT tool to plot the 3 points at which the lines (you constructed in steps 4 - 6) intersect the 3 sides of the triangle.
8) Go to the STEPS window. Hide the 3 lines you constructed in steps 4 - 6.
9) Construct a circle with centered at the incenter that passes through any 1 of the points you constructed in step 7.
10)
What do you notice? Why does this occur?
When you're done (or if you're unsure of something), feel free to check by watching the quick silent screencast below the applet.