The Law of Cosines can be used.
If the given angle is opposite one of the given sides, the Law of Sines can be used.
Law of Cosines:
.. c^2 = a^2 +b^2 -2ab*cos(C) . . . . . for any permutation of sides a, b, c, and opposite angle C
Law of Sines:
.. a/sin(A) = b/sin(B) = c/sin(C)