The Sine Rule is used to Cloze (1): JXUwMDJiJXUwMDFjJXUwMDAzJXUwMDFhJXUwMDEz any problems involving Cloze (2): JXUwMDJjJXUwMDA2JXUwMDFiJXUwMDA4JXUwMDBmJXUwMDA5JXUwMDBiJXUwMDA5JXUwMDE2 when at least either of the following is known: two Cloze (3): JXUwMDM5JXUwMDBmJXUwMDA5JXUwMDBiJXUwMDA5JXUwMDE2 and a Cloze (4): JXUwMDJiJXUwMDFhJXUwMDBkJXUwMDAx or two Cloze (5): JXUwMDJiJXUwMDFhJXUwMDBkJXUwMDAxJXUwMDE2 and an Cloze (6): JXUwMDM5JXUwMDBmJXUwMDA5JXUwMDBiJXUwMDA5 opposite a given Cloze (7): JXUwMDJiJXUwMDFhJXUwMDBkJXUwMDAx .

In Triangle ABC, we use the convention that a is the side Cloze (8): JXUwMDM3JXUwMDFmJXUwMDAwJXUwMDFmJXUwMDFjJXUwMDFhJXUwMDFkJXUwMDEx angle A, Cloze (9): JXUwMDNh is the side opposite angleB and c is the side opposite angle Cloze (10): JXUwMDFi . The sine rules enable us to calculate Cloze (11): JXUwMDJiJXUwMDFhJXUwMDBkJXUwMDAxJXUwMDE2 and Cloze (12): JXUwMDM5JXUwMDBmJXUwMDA5JXUwMDBiJXUwMDA5JXUwMDE2 in some triangles where there is no a Cloze (13): JXUwMDJhJXUwMDFiJXUwMDBlJXUwMDBmJXUwMDFj angle.

Using a label triangle, the sine rule is stated as:

1. Use when finding a side 

    a   =         Cloze (14): JXUwMDNh       =       c

   Cloze (15): JXUwMDJiJXUwMDFhJXUwMDA3JXUwMDRlJXUwMDYx      sin B         Cloze (16): JXUwMDJiJXUwMDFhJXUwMDA3JXUwMDRlJXUwMDYz

2. Use when finding an angle

   sin A = Cloze (17): JXUwMDJiJXUwMDFhJXUwMDA3JXUwMDRlJXUwMDYy   =     sin C

      Cloze (19): JXUwMDM5             b              Cloze (22): JXUwMDNi