Confused on law of cosines with the given SAS values

Question

I have 

a = 65

b = ?

c = 50

 

<A = ?

<B = ?

<C = 52

 

Now I understand the b² = a² + c² - 2ac*CosB and the other 2 variants of the formula but how do I solve it when I don't have a value to put for Cos B in the formula above?

Answer 1

Well, you could use the Law of Sines to find <A (sinA/a = SinC/c), and then get <B by 180 - (<A+<C).  That lets you calculate Cos B.

Answer 2

You are given the lengths of side a and c. To use the Law of Cosines you wold need to know m∠B.

Try the Law of Sines.