ASS Theorem

Specifying two adjacent side lengths $a$ and $b$ of a Triangle (taking $a>b$) and one Acute Angle $A$ opposite $a$ does not, in general, uniquely determine a triangle. If $\sin A < a/c$, there are two possible Triangles satisfying the given conditions. If $\sin A = a/c$, there is one possible Triangle. If $\sin A > a/c$, 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