1. Angle Geometry
Angles in a Triangle

2. Explore the Wonders of Math
PART 1
With a partner, draw 2 identical copies of a right triangle, an acute triangle, and an obtuse triangle on dot paper (6 total). Label each angle.
Cut one right triangle and cut it into 3 pieces. Place the labelled angles together, so their vertices are at the same point. What do you notice?
Repeat the activity with an acute triangle and an obtuse angle. What do you notice?
What can you say about the sum of the angles in the triangles you drew?
Explore the Wonders of Math

3. Explore the Wonders of Math
PART 2
Use the second copy of your triangles. Measure each angle with a protractor and label it with its measure.
Find the sum of the angles in each triangle.
Does this confirm your results from cutting the triangles into 3 pieces? Explain.
What can you conclude about the sum of the angles in all of your 6 triangles?
Explore the Wonders of Math

4. Adventures of Mr. Triangle
The measures of the internal angles in a triangle add to 180°.
You can use the sum of the internal angles to find unknown angle measures in triangles.
Complimentary angles can also assist in finding unknown angle measures.
Key Ideas
Adventures of Mr. Triangle

5. What strategies would you use to solve the angles on the document camera?
Activity:
With a partner, solve the various angles at each station. Remember to use the rules from today and last lesson.
Examples & Activity