Answer:
B = 34.77°
Step-by-step explanation:
For this problem you are given all three side lengths and asked to find an angle. To do this you can use the law of cosines which is written:
[tex]b^{2} =a^{2} +c^{2} -2ac Cos(B)[/tex]
This can be rearranged to find the angle B:
[tex]b^{2} -a^{2} -c^{2} /-2ac = Cos(B)[/tex]
With lowercase letters being sides and uppercase being angles.
We simply plug in the sides and solve:
[tex]4^{2} -6^{2} -7^{2}/-2*6*7= Cos(B)[/tex]
0.8214 = Cos (B)
Then you use inverse cosine to get angle B alone.
B = 34.77°
