To bisect an angle, (in this case angle B), draw an arc with the center at the vertex at the center of the angle, as shown. Put points A and C where the arc intersects the sides of the angle. Using A and C as centers and any radius, draw two intersecting arcs. The line though this point (call it D, not shown) and point B bisects angle B, (alternately named angle ABC).

Click here to return to Ian's Geometry Forum.