In Exercises 1-10, use the law of cosines to approximate the required part of triangle ABC. Problem 2: If a=5,b=12, and c=15, find γ. Problem 4: If b=20,c=13, and α=19 ∘
10 ∘
, find a. Problem 6: If a=30,c=40, and β=122 ∘
, find b.