The Law of Sines is an equation relating the sides of a triangle to the sines of its angles. This law is also known as Sine Law, Sine Formula or Sine Rule. According to Law of Sines:
where a, b, and c are the lengths of the sides of the triangle, and A, B and C are the opposite angles. As shown in the figure below side a faces angle A, side b faces angle B and side c faces angle C.
The equation can also written using the reciprocal of the above equation:
Law of sines is used when:
Case 1: When2 sides and an angle are given and an angle opposite a known side is to be measured.
Case 2: When 2 angles and a side are known the side opposite a known angle is to be measured.