Triangle ABC has B= 137degrees, A=31.6 in., and C=42.8 in. Find B.
Assuming that A is the side opposite angle A, etc.
Use the law of cosines:
B^2 = A^2 + C^2 - 2AC cosB
= 31.6^2 + 42.8^2 - 2(31.6)(42.8)(-.7313)
= 4808.53
B = 69.3
Use the law of cosines:
B^2 = A^2 + C^2 - 2AC cosB
= 31.6^2 + 42.8^2 - 2(31.6)(42.8)(-.7313)
= 4808.53
B = 69.3