Trigonometry

For planar triangles of sides A, B and C with opposing angles $\alpha$, $\beta$, and $\gamma$, one has

1.

Law of Cosines

There is a typo in the following (thanks Mike Daly). It should read 2 B C cos etc..

$$A^2 = B^2 + C^2 -2 BC \cos \alpha$$

2.

Law of Sines

$$\frac{\sin \alpha}{A} = \frac{\sin \beta}{B} = \frac{\sin \gamma}{C}$$

3.

Inverse Functions

If $\sin x = y$ then y = sin^-1 x.