Line segment operations

COPYING A LINE SEGMENT
This page shows how to copy a line segment with compass and straightedge or ruler. Given a line segment, this shows how to make another segment of the same length.

• Step-by-step instruction sheet.
• Try it yourself.

ADDING UP LINE SEGMENTS (in your notebooks)

The addition of two segments is another segment that begins at the origin of the first segment and ends at the end of the second segment.

STEPS:

1. Draw a line (r).
2. Draw a point A on it. (step 1 and 2 could be given)
3. Measure the given segment AB with your compass.
4. Draw an arc from A with that measure, so you get B.
5. Measure the given segment CD with your compass.
6. Draw an arc from B with that measure, so you get D.
7. The solution is the segment AD.

SUBTRACTING LINE SEGMENTS (in your notebooks)

STEPS:

1. Draw a line (r).
2. Measure the longest segment with your compass, in our case is the segment CD.
3. Draw a point C on r. (step 1 and 3 could be given)
4. Draw an arc from dot C with the previous measure (the segment CD), so you get D.
5. Measure the smallest segment with your compass, in our case is the segment AB.
6. Draw an arc from D with that measure, so you get B.
7. The solution is the segment CB.