1. Sine Law Homework Questions??? Pg. 25 # 3, 5, 7, 9

2. Unit 1 The Cosine Law Learning Goal: I can Solve for a missing side or angle in a non-right triangle using cosine law

3. Recall: Sine Law Matching side and angle

4. Cosine Law We can solve for the third side We can solve for any angle

5. Example 1 How do you know you can use cosine law to solve this problem? Could we also use sine law? Label the sides of the triangle a, b, and c Calculate the missing side using cosine law 73⁰ 2.3 km 1.9km ? C A B

6. Example 2 How do you know you can use cosine law to solve this problem? Could we also use sine law? Label the sides of the triangle x, y, and z Calculate the missing side using cosine law (rewrite equation first) X Y Z 28⁰ 12.3 m11.9 m x

7. Example 3 How do you know you can use cosine law to solve this problem? Could we also use sine law? Label the sides of the triangle a, b, and c Calculate the angle B using cosine law 3.3 cm 3.8 cm 2.7 cm A B C

8. Practice Pg. 35-38 # 3, 5, 8, 9