How to Bisect an Angle Using a Compass
To bisect an angle, you use your compass to locate a point that lies on the angle bisector; then you just use your straightedge to connect that point to the angle’s vertex.
Try an example.
Refer to the figure as you work through this construction:
- Open your compass to any radius r, and construct arc (K, r) intersecting the two sides of angle K at A and B.
- Use any radius s to construct arc (A, s) and arc (B, s) that intersect each other at point Z.
Note that you must choose a radius s that’s long enough for the two arcs to intersect.
- Draw line KZ and you’re done.