Construction: Midpoints

About Geometry Worksheet Activity 1C:  

 

Activity 1C is practice for construction of midpoints of line segments.

 

Prerequisite Skill: Identify and name midpoints (Assignment 1.16)

 

How to construct the midpoint of a line segment:

 

(Do problem 1 by following the steps below.)

 

1.   Place the compass point at an endpoint (S) of the given line segment.

 

2.   Open the compass pencil more than halfway to the other endpoint (T).  Draw a long arc (at least half of a circle.) 

 

3.   Do not change the compass opening.  Place the compass point at the other endpoint (T) of the line segment..

 

4.   Using the same compass opening, draw an long arc that intersects the first arc above and below the line segment.

 

5.   Use a straightedge to draw a line through the two points of intersection of the long arcs.  

 

6.   The midpoint is at the intersection of the line with the given line segment.