Construct the bisector of the following figures :

1. Draw an circle centred at B, using a radius that is longer than half of the length of AB.
2. Using the same radius, draw an circle centred at A (and at C) to cut the previous circle.
3. Join points of intersection as shown in the picture. These two lines (PS and RS) are arc  bisectors. 
4. The point of intersection is a center of a circle which passes through points A,B,C.