Bisect means to cut into 2 equal parts . If you bisect a 90 degree angle you create two 45 degree angles, as shown in diagram 1 below:
Diagram 1![bisected angle](images/picture-of-angle-bisector.png)
![bisected line segment](images/picture-of-bisector-of-line-segment.png)
You can also bisect a segment. For instance segment AB is bisected by point C because point c divides the segment up into 2 smaller segments of equal length.