How do you divide a line into 3 equal parts?
1. Using a ruler, draw a straight line that starts at one end of the line to be trisected (the "original" line) and forms an angle with it that is some number of degrees less than 90. 2. Using a compass (the drawing kind, not the navigating kind), set some distance on it, say, 2 inches.
3. Putting the point at the intersection of the original line and the one you just drew, make a mark with the pencil end that intersects the line you just drew. Place the point on that intersection point and repeat. Now move the compass and repeat again.
4. From the point at which your third mark intersects the line you drew in step 1, draw a straight line to the end of the original line.
5. Using a protractor, measure the angle formed by the line you drew at step 1 and the step 4 line.
6. With the protractor draw a line from the second mark to the original line that has the same angle as the line in step 5.
7. With the protractor draw a line from the first mark to the original line that has the same angle as the line in step 5.
8. Take a break!
For another method of trisecting a line segment, please follow the link.