A triangle (up to congruence) can be specified in various ways. The different information given is represented by the acronyms:
SSS | three sides’ lengths are specified; |
SAS | two sides and the angle they subtend are specified; |
SSA | two sides and an angle, different from the one they subtend, are specified; |
ASA | a side and the two angles adjacent to it are specified; |
AAS | a side, an adjacent angle and the opposite angle are specified. |
In each case, the triangle can be entirely determined by applications of the sine and cosine rules and knowing that the angles sum to 180 degrees.