Which of these triangles can you use the law of cosines to solve for a missing side?

A triangle has angle 75 degrees and 38 degrees. A side with length 8 is between the 2 angles. A side with length x is opposite to the angle with measure 75 degrees.

A triangle has side lengths x, 8, and 12. The angle opposite to side x has a measure of 138 degrees.
A right triangle is shown. The hypotenuse has length x and another side has length y. The angle opposite to side y is 35 degrees.

A triangle with 3 angle measures of 60 degrees is shown. The side lengths are x.

Law of Cosines
Assignment

Determining When to Use the Law of Cosines

Its B.