Law of Sines

Theorem
For any triangle $\triangle ABC$:


 * $\dfrac a {\sin A} = \dfrac b {\sin B} = \dfrac c {\sin C} = 2 R$

where:
 * $a$, $b$, and $c$ are the sides opposite $A$, $B$ and $C$ respectively
 * $R$ is the circumradius of $\triangle ABC$.

Also presented as
Some sources do not include the relation with the circumradius, but instead merely present:


 * $\dfrac a {\sin A} = \dfrac b {\sin B} = \dfrac c {\sin C}$

Also known as
This result is also known as the sine law, sine rule or rule of sines.

Also see

 * Law of Cosines