M 333 L
SPRING 2017
Lab Assignment #2
Note: If, when making calculations, clicking on the measurement report fails to enter the measurement into the
Sketchpad Calculator for calculating, then, before opening the Sketchpad Calculator, select all of the
measurement reports that you will need for your calculation and then open the Sketchpad Calculator. The
values selected are now listed for use in the "Values" Menu button, just above the "Functions" Menu button.
Make 4 sketches each showing a triangle with measurements and ratio calculations that illustrate the truth of
Theorem (NIB) 4.2 , the "Angle Bisector Third Side Cut" Theorem.
On each sketch, in a caption, describe how the sketch illustrates the truth of Theorem (NIB) 4.2,
The "Angle Bisector Third Side Cut" Theorem.
Drag the vertices of each triangle so that the triangle in each sketch has the required ratio.
(See the ratio list at the end of these instructions.)
Print out each sketch to turn in. Always use "Print Preview" first and select "Fit to Page".
Sometimes you must lower the percent reduction slightly still.
On each sketch:
1) Label the vertices of the triangle A, B, and C.
2) Construct the angle bisector of  BAC .
[ Do this by selecting B, A, and C in order
and then select “Angle Bisector” on the Construct menu. ]
3) Construct the point where the angle bisector and the side BC intersect and label this point D .
4) Measure angles  BAD and  CAD .
5) Measure the distances AB , BD, DC, and AC .
6) Calculate the two ratios of segments
discussed in the statement of Theorem (NIB) 4.2,
The "Angle Bisector Third Side Cut" Theorem .
Calculate these ratios using the Calculator in the "Measure" Menu, selecting (by clicking on) the measurements
reported by the Sketchpad program OR by selecting the measurement reports before opening the Sketchpad
calculator and then retrieving the values from the "Values" Menu after opening the Sketchpad calculator.
[The names of the segments you use will be different from the names of the segments used in the
theorem.]
Make sure that the two ratios you calculate are equal.
For Sketch #1, the ratio must be between 0.19 and 0.21, but try to make it 0.20 exactly.
For Sketch #2, the ratio must be between 0.74 and 0.76, but try to make it 0.75 exactly.
For Sketch #3, the ratio must be between 0.9 and 1.1, but try to make it 1.0 exactly.
For Sketch #4, the ratio must be between 7.4 and 7.6, but try to make it 7.5 exactly.