Visualizing the Angle Sum in a Triangle
Task
Create an interactive figure that allows your students to explore the angle sum in a triangle.
Instructions
1. | Create a triangle ABC with counter clockwise orientation. | |
2. | Create the angles α, β and γ of triangle ABC. | |
3. | Create a slider for angle δ with Interval 0 ̊ to 180 ̊ and Increment 10 ̊. | |
4. | Create a slider for angle ε with Interval 0 ̊ to 180 ̊ and Increment 10 ̊. | |
5. | Create midpoint D of segment AC and midpoint E of segment AB. | |
6. | Rotate the triangle around point D by angle δ (setting clockwise). | |
7. | Rotate the triangle around point E by angle ε (setting counter clockwise). | |
8. | Move both sliders δ and ε to show 180 ̊. |
Try it yourself...
Instructions (continued)
9. | Create angle ζ using the points A’C’B’. | |
10. | Create angle η using the points C'1B'1A'1. | |
11. | Enhance your construction using the Style Bar. Hint: Congruent angles should have the same color. | |
12. | Create dynamic text displaying the interior angles and their values (e.g. enter α = and select α from the list of objects on tab of the Advanced section). | |
13. | Calculate the angle sum by entering sum = α + β + γ in the Algebra Input. | |
14. | Insert the angle sum as a dynamic text: α + β + γ = and select sum from the list of objects on tab . | |
15. | Match colors of corresponding angles and text using the Style Bar. | |
16. | Fix all texts that are not supposed to be moved by using the Style Bar. |