1. LAW OF SINE AND COSINE UNIT 5 – 6 USE ON ALL TRIANGLES!!!!

2. WHAT IS THE LAW OF SINE AND COSINE ?? YOU CAN USE THE LAW OF SINE AND LAW OF COSINE ON ALL TRIANGLES. SOH CAH TOA IS ONLY USED ON RIGHT TRIANGLES. LAW OF SINE AND LAW OF COSINE CAN BE USED ON ACUTE, OBTUSE, AND RIGHT TRIANGLES.

3. LAW OF SINE LAW OF SINE IS SET UP AS A PROPORTION OF THE ANGLE OVER THE OPPOSITE SIDE LABEL YOUR TRIANGLE BEFORE SETTING UP THE RATIOS FOR LAW OF SINE CAPITAL LETTERS ARE ANGLES (NOT ALWAYS A, B, C) LOWER CASE LETTERS ARE THE OPPOSITE SIDE A a B b C c

4. LAW OF COSINE LAW OF COSINE IS SET UP AS AN EQUATION, THAT STARTS WITH THE SIDE SQUARED. LABEL YOUR TRIANGLE BEFORE SETTING UP THE RATIOS FOR LAW OF COSINE CAPITAL LETTERS ARE ANGLES (NOT ALWAYS A, B, C) LOWER CASE LETTERS ARE THE OPPOSITE SIDE A a B b C c

5. Example # 1 Use Law of Sine If m A = 37 o, m B = 68 o, and a = 3, find the length of side b and the m C

6. Example # 2 Use Law of Sine If b = 17, c = 14, and m B = 92 o find the m C, and the length of side a You draw the triangle – use a straight edge

7. Example # 3 Find the measure of angles S, T, and P Use Law of Cosine S T P 10 12 11

8. Example # 4 Find the measure of angles R, S, Q Use Law of Cosine R Q S 18 37 23