1. Warm Up
Solve ΔSJT given s = 49, side j = 16, and angle S = 115°. S = _____ J = _____ T = _____ s = _____ j = _____ t = _____

2. Answer
Solve ΔSJT given s = 49, side j = 16, and angle S = 115°. S = 115° J = 17.21° T = 47.79° s = 49 j = 16 t = 40.05

3. Law of Cosines

4. Remember how we need buddies to use the Law of Sines?
In order to use the Law of Sines, we need “buddies.” What if we don’t have buddies?

5. Law of Cosines!
a2 = b2 + c2 – 2bc cos A b2 = a2 + c2 – 2ac cos B c2 = a2 + b2 – 2ab cos C
We decide which equation to use by using the angle we have (or the angle we want to find!).

6. Example 1: No buddies, no problem!
Solve ΔABC given that a = 11, b = 8, and angle C = 37°. A = _____ B = _____ C = _____ a = _____ b = _____ c = _____

7. Example 2: You try!
Solve ΔABC if a = 9, b = 7, and c = 5. A = _____ B = _____ C = _____ a = _____ b = _____ c = _____