Purpose: To familiarize the student with an introduction to the TI-92 geometry software in order to discover the vertical angles and linear pair relationships.
1. Turn on the calculator. If your cursor is "big" ( ), change it to a small cursor
by pressing 2nd <--. Make sure you check for the skinny cursor right after you turn the
TI-92 on. If you don’t do this now, you will not be able to label your sketches.
2. To get into Cabri Geometry:
APPS, 8 (Geometry)
To get into current screen:
1(Current)
To get into a new screen:
3 (New)
Arrow down (cursor) to variable
Put in your initials or use a file name such as gw4 (g = geometry, w = your
teacher’s last name initial, 4 = your period.)
3. Delete your previous work by clearing your screen (F8, option 8).
4. To turn on caps lock, press 2nd Z. Note: Every time you leave and return to the
geometry application you must reset caps lock by pressing 2 nd Z to get capital
letters. (Even if your calculator shuts down by itself using the automatic battery
saving feature.) If you can’t put in comments, you probably have a big cursor.
The big cursor means the calculator is in typeover mode instead of the insert
mode when the little cursor is displayed.
5. If your screen is locked up, press 2nd, Hand, ON keys simultaneously to reboot.
6. Labels and Comments-
a. Always label and comment IMMEDIATLEY.
b. If you forget to label as you go, you can add them later in F7.
c. Labels are for Points, Segments, Triangles, Lines, Polygons.
d. Comments are for numbers.
7. If you want more or less decimal places in your numbers: select the number, then
press + or -.
8. Frequently used keys
ESCAPE = pointer
<&rt; Z = undo
F8, 8 = Clear screen
2nd Z = Caps lock and unlock
<&rt; + = brighten the display
<&rt; - = dim the display
Press 2nd and cursor pad at the same time = scrolls the drawing window
9. Dragging-
a. To know what you can drag: POINTER (Esc); if you hold down hand movable
items flash
b. up arrow : select multiple objects
10. To turn calculator off-
a. 2 nd on or
a. <&rt; on (This will turn the calculator off while still in Cabri Geometry.)
11. Pressing enter- Be careful to press enter only once. If you have a heavy touch or
are pressing enter more than once, you’ll be adding extra points and all of your
answers will be wrong. You will know if you have more than one point by using
the pointer tool (F1, option 1 or pressing esc) and pointing at an object. If the
message "which object" appears, press enter and then press the backspace key.
The unwanted object will disappear form your screen.
Discovery of Angle Relationships using the TI-92
1. Construct 2 lines (F2, option 4: line). Do NOT have the lines perpendicular.
2. Construct and label points C, T, W, V, and X on the lines you constructed in step
1. (F2,Option 1: point).
3. Measure < TVC and < WVX (F6, option 3: angle).
m<TVC = _____________ m<WVX = ____________
4. Can you develop a conjecture about how these angles are related?
5. Measure < XVC and < WVT (F6 option 3: angle).
m<TVC = ___________ m<WVX = ____________
6. Can you develop a conjecture about how these angles are related?
7. Look at all four angle measurements. What other conjectures can you make about
the relationships between the four angle measurements? Remember to use as much correct geometry terminology as possible.
Helpful Hints and TI-92 Lesson both developed by Lisa Willian, 1998 Kentucky Christa McAuliffe Fellow from a presentation and handouts from the 1998 T3 Conference, Chicago, Illinois given by Linda Byrom and Larry Scalzitti, Adlai Stevenson High School, Lincolnshire, Illinois. Permission granted for classroom use only.
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