User blog comment:John Lee Gamma Guild Team Vi Hart/Law of cosines/sines question???/@comment-25501845-20150828014432

It depends on the Picture, if you could draw the picture I could easily find it out =)

But, just for a tip Law of sines is applicable :-

1) If two sides and one of the opposite angle is given where the objective is to find the other angle opposite to the side.

2) If two angles and one of the opposite side is given and the objective is to find out the other opposite side.

Law of cosines are applicable:-

1) If 2 sides and the included angle are given and the objective is to find the side opposite to the angle.

2) If 3 sides are given and the objective is to find out any angle(Which might be your case)