1. TI-Nspire App Tutorial
The Perpendicular Bisectors of a
Triangle

2. Summary
• In this tutorial, you’ll be constructing the
perpendicular bisectors of the sides of a
triangle. The steps in the tutorial include:
– Creating a Geometry Window.
– Constructing a triangle.
– Finding the midpoints of the three sides.
– Finding the perpendicular bisectors of the three
sides.

3. Create a Geometry Window
Click on the + tool to activate this menu.

4. Create a Geometry Window
This is a blank Geometry Window.

5. Construct a Triangle
Click on Menu and select Points & Lines > Segment.

6. Construct a Triangle
Press once to define the left endpoint. Then press again to
define the right endpoint. Make sure it’s horizontal.

7. Construct a Triangle
Activate the Segment tool again.

8. Construct a Triangle
Construct the second side.

9. Construct a Triangle
Activate the Segment tool again.

10. Construct a Triangle
Construct the third side.

11. Find the Midpoint of Each Side
Press Menu and click Tools > Measurement > Midpoint.

12. Find the Midpoint of Each Side
Press on a side to create the midpoint.

13. Find the Midpoint of Each Side
Activate the Midpoint tool again.

14. Find the Midpoint of Each Side
Press on the second side to create the midpoint.

15. Find the Midpoint of Each Side
Activate the Midpoint tool again.

16. Find the Midpoint of Each Side
Press on the third side to create the midpoint.

17. Construct a Perpendicular Line
Click on Menu and press Perpendicular.

18. Construct a Perpendicular Line
Press on the Midpoint of one of the sides. You can also extend
the perpendicular line by clicking and dragging it.

19. Construct a Perpendicular Line
Select the Perpendicular tool again.

20. Construct a Perpendicular Line
Press on the Midpoint of the second side.

21. Construct a Perpendicular Line
Select the Perpendicular tool again.

22. Construct a Perpendicular Line
Press on the Midpoint of the third side. Notice that all three
bisectors meet at one point.

23. Construct the Intersection Point
Press on Menu and select Tools > Points & Lines > Point.

24. Construct the Intersection Point
Press on two of the Perpendicular Bisectors to create the
intersection point.

25. Manipulate the Triangle
Manipulate the vertices to change the triangle. You’ll see the
bisectors intersect at one point.