
How to bisect a given angle? How to divide it into two equal parts?

1. 
 Start with the given angle.


2. 
 Draw an arc with its center at the angular point, and a suitable radius.


3. 
 Draw an arc with its center at the intersection of arc 2 and one leg of the angle, and a suitable radius (more than "halfway" the angle).


4. 
 Draw an arc with its center at the intersection of arc 2 and the other leg of the angle, and a radius equal to that of arc 3. Arcs 3 and 4 must intersect.


5. 
 Draw a line from the angular point to the intersection of arcs 3 and 4.


6. 
 Line 5 is the bisector of the angle; it divides the angle into two equal parts.

