Specifying two adjacent side lengths and of a triangle (with ) and one acute angle opposite does not, in general, uniquely determine a triangle.
If , there are two possible triangles satisfying the given conditions (left figure). If , there is one possible triangle (middle figure). If , there are no possible triangles (right figure).
Remember: Don't try to prove congruence with the ASS theorem or you will make an ASS out of yourself.
An ASS triangle with sides and and excluded angle with has two possible side lengths ,
The SSS or SAS theorems can then be used with either choice of to determine the angles and and triangle area .