Law of Sines

Theorem
Let $\triangle ABC$ be a triangle whose sides $a, b, c$ are such that $a$ is opposite $A$, $b$ is opposite $B$ and $c$ is opposite $C$.

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

where $R$ 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
 * Law of Tangents