Specifying two adjacent side lengths and of a Triangle (taking ) and one Acute Angle opposite does not, in general, uniquely determine a triangle. If , there are two possible Triangles satisfying the given conditions. If , there is one possible Triangle. If , there are no possible Triangles. Remember: don't try to prove congruence with the ASS theorem or you will make make an ASS out of yourself.
See also AAA Theorem, AAS Theorem, SAS Theorem, SSS Theorem, Triangle