The law of sines is used to find the remaining sides of a triangle when two angles and a side are known. This is known as triangulation. The law of sines can also be used when two sides and one of the angles not enclosed by the two sides are known. In some such cases, the formula gives two possible values for the enclosed angle. This is called an ambiguous case.
The law of sines is one of two trigonometric equations which is used to find lengths and angles in scalene triangles. The other is the law of cosines.