Construction: Angle Bisectors

About Geometry Worksheet Activity 2C:       

 

Activity 2C is an introduction to the construction of the bisector of an angle.

 

Prerequisite Skills: Name angles (Assignment 2.4).  Name angle bisectors (Assignment 2.15).

 

How to construct the bisector of an angle with a compass and straightedge:

 

(Do problem 1 by following the steps below)

 

1.  Place the compass point at Q.

 

2.  Draw an arc crossing both sides of the angle (<Q).

 

3.  Place the compass point at the intersection of the arc and one side (QT) of the angle.

 

4.  Open the compass to the intersection of the arc and the other side (QS) of the angle.

 

5.  Draw an arc in the interior of the angle.

 

6.  Place the compass point at the intersection of the arc and the other side (QS) of the angle.

 

7.  Using the same compass opening, draw an arc intersecting the arc in the interior of the angle.

 

8.  Place a point at the intersection of the arc. Label the point R.

 

9.  Use a straightedge.  Draw a ray from the vertex (Q) throught the point of intersection (R) of the arcs.

 

10.  Ray QR is the bisector of <SQT.