Question

How do I do number 1?

Answer 1

Answer: 16.8

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Explanation:

The lower case letters represent the side lengths. 
The uppercase letters represent the angles. 
Side 'a' is opposite angle A
Side 'b' is opposite angle B
Side 'c' is opposite angle C

Angle A is 62 degrees because you would solve A+B+C = 180 for A. Or you can compute 180-B-C = 180-82-36 to get the same result for angle A.

Once you know the measure of angle A, you can use the law of sines

sin(A)/a = sin(B)/b
sin(62)/15 = sin(82)/b
b*sin(62) = 15*sin(82)
b = 15*sin(82)/sin(62) 
b = 16.8232193521557 <<--- see note below
b = 16.8

note: use a calculator for that step. Make sure the calculator is in degree mode