MAFS.912.G-CO.4.12 Practice Lesson

You are given the Line Segment AB

Step 1: Using your compass, draw an arc that is AT LEAST half the distance from A to B

Step 2: Without changing the compass measurement, place the compass at point B and draw another arc

Where your two arcs cross will create two more points. In the example those are Point X and Point Y

Step 3: Draw a line through Point X and Point Y

Where your new line, Line XY, crosses Line Segment AB is the midpoint, M.

Perpendicular: where two lines cross and create 90 degree angles. Bisector: Splits what it crosses in half, sometimes creating a midpoint.

Step 1: Open the compass about two-thirds of the distance of one ray coming from Angle A.

Step 2: Create and arc with the compass until It crosses the other ray of Angle A

The new points created by the arc are Point B and Point C

Step 3: Using the compass, measure the distance from Point A to Point B

Step 4: Preserve the measurement and place the point of the compass on Point S and the pencil end on the ray.

Where the pencil sits on the ray is going to be Point R

Step 5: Create an arc from Point R

(You may be asked what to find a congruent line segment. In this example, Line Segment AC is congruent to SR)

Now that you have created the new arc coming from point R

Step 6: Using the compass, measure the distance from Point B to Point C

Step 7: Put the point of your compass at Point R and create another arc. Where the two arcs cross will be a new point, Point T

Hint: (The arc from B to C is congruent to the arc from T to R)

Step 8: Construct a ray from Point S through Point T

The angle created is Angle S, and it is congruent to Angle A

You are given Angle A

Step 1: Create an arc by putting your compass at Point A and drawing the arc through both rays that come out of Point A

The new points created are B and C

Step 2: Place your compass at point B and draw an arc

Step 3: Place your compass at point C and draw an arc

Where the two new arcs cross is Point D

Step 4: Draw a ray coming out of Point A and through Point D

The new ray is the Angle Bisector

The angle bisector splits the angle in half