1. Class Greeting

2. Objective: The students will be able to find missing angles of triangles.

3. Chapter 4 – Lesson 1
Angles of Triangles

4. Triangle Sum Theorem (Theorem 4.1)

5. Find the missing angle measures.
Answer:
Example 2-1a

6. Find the missing angle measures.
Answer:
Example 2-1b

7. Vocabulary Exterior Angle
The angle formed by one side of a triangle and the extension of another side

8. Vocabulary Remote interior angles (of an exterior angle)
The angles of a triangle not adjacent to the exterior angle

9. Exterior Angle Theorem (Theorem 4.2)

10. Find the measure of each numbered angle in the figure.
102 37 46 70
Exterior Angle Sum
110
Answer:
and
Example 2-2a

11. Find the measure of each numbered angle in the figure.
Answer:
Example 2-2b

12. Corollary 4.1 The acute angles of a right triangle are complementary.
Corollary There can be at most one right angle or one obtuse angle in a triangle.

13. GARDENING The flower bed shown is in the shape of a right triangle
GARDENING The flower bed shown is in the shape of a right triangle. Find if is 20.
Answer:
Example 2-3a

14. The piece of quilt fabric is in the shape of a right triangle
The piece of quilt fabric is in the shape of a right triangle. Find if is 42. 42 48
Answer:
Example 2-3b

15. Kahoot!

16. Lesson Summary:
Objective: The students will be able to find missing angles of triangles.

17. Preview of the Next Lesson:
Objective: The students will be able to identify congruent triangles, find corresponding parts of congruent triangles and transform congruent triangles.

18. Stand Up Please