Purpose: Students will investigate how SSS will guarantee congruent triangles using TI-82’s or TI-83’s.

Teacher’s Note: If graphing calculators are not available, only complete part two.

Materials Needed: Graphing calculators (TI-82’s or TI-83’s), graph paper, straight edge.

Part One:

Graph triangle ABC with vertices A(3,4), B(12,4), C(6,14) and triangle XYZ with vertices X(-4,-2), Y(-4,-11), Z(-14,-5) using the directions below for the graphing calculator.

1. Press ZOOM 6

2. Press ZOOM 8 ENTER

3. Press 2nd DRAW 2

4. Use the arrow keys to move the cursor to (3,4). The coordinates should be shown at the bottom of the screen. When your cursor is at (3,4), press ENTER.

5. Now move the cursor to point B(12,4). Press ENTER twice.

6. Move the cursor to point C(6,14) and press ENTER twice.

7. Then move the cursor back to point A to complete the triangle. Press ENTER.

8. Repeat the steps 4-7 above using the coordinates of triangle XYZ to draw the second triangle.

Questions:

1. How do the size and shape of triangle ABC and triangle XYZ compare? ___________________

2. If you placed triangle ABC on top of triangle XYZ, which angles would be congruent? ________________________________________________________________________________

3. Which sides would be congruent? __________________________________________________

Part two:

1. Now plot the above points on graph paper to create the two triangles. Remember to label the points.

2. Which angles appear to be congruent now? _______________________________________

3. Which segments appear to be congruent now? _____________________________________

4. Using the distance formula, calculate the length of each segment. Show work. AB = ________ AC = __________ BC = ___________ XY = ___________ YZ = ____________ XZ = ____________

5. Write a paragraph that explains why these two triangles are congruent or not.











Developed by the "Geometry for All" network for the 1998 Kentucky Christa McAuliffe Fellowship, Lisa Willian, fellow. Permission granted for classroom use only.

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