Trigonometry

Woof. Super rusty.

$sin$ = given an angle, output a number. $si{n}^{-1}$ should do the opposite.

I think I need to memorize the trigonometric identity functions

• DONE Completed: 2022-06-08

One of them, at least, is $si{n}^2(x)+co{s}^2(x)=1$ and we can do simple algebra to isolate one or the other function. $ta{n}^2(t)+1=se{c}^2(t)$ $se{c}^2(x)-1=ta{n}^2(x)$

$1+co{t}^2(t)=cs{c}^2(t)$

Half angle functions: $si{n}^2(x)=\frac{1-cos(2x)}{2}$ $co{s}^2(x)=\frac{1+cos(2x)}{2}$

Double angle function $sin(2x)=2sin(x)cos(x)$

$\begin{array}{r}ta{n}^2\theta =se{c}^2\theta -1\end{array}$