CONSTRUCTION DAY!Segment and Angle

Bisectors

LEARNING TARGETS:1. I will be able to construct line segment bisectors and angle bisectors with a compass and straightedge.

Video

Constructing Line Segment Bisectors:

http://www.youtube.com/watch?v=5bvjnleMn5A&feature=related

STEP 1:

Set your compass width to more than half of the length of the segment you are trying to duplicate.

A B

STEP 2:

Place the needle end of your compass on point A and make a half circle with the compass.

A B

STEP 3:

Place the needle end of your compass on point B and make a half circle with the compass.

A B

STEP 4:

Make two points where each arc intersects.

A B

STEP 5:

Connect the two points with a line using your straightedge.

A B

Conclusion:

Segment AB is divided into two congruent segments.

A B

Guided Practice:

•Complete problem #1 on your Construction Worksheet using a compass and straightedge together with the teacher.

A B

Video

Constructing Angle Bisectors:

http://www.youtube.com/watch?v=z8y2me2XFYE&feature=related

STEP 1:

Set your compass to a default length. Set your needle on the vertex of the angle and draw an arc that intersects both rays.

A

STEP 2:

Set your compass to a default length (you may keep it the same length). Set your needle on each of the angle’s rays and the intersection of the arc. Make a small arc in the middle of the angle.

A

STEP 3:

Make a point at where the two small arcs intersect. Draw a ray from the angle’s vertex through the point you just created.

A

CONCLUSION:

Angle A is now cut in half and there is now two congruent angles.

A

Guided Practice:

•Complete problem #2 on your Construction Worksheet using a compass and straightedge together with the teacher.

A

Cooperative Learning

•Problems #3-6 on Constructions Worksheet•Use Compass and Straightedge.

HOMEWORK•Lessons 2.1 and 2.2 Review Worksheet

•Due Thursday, 10/20