Sec, cosec, cot and inverse trig

The idea

$\sec x = \frac{1}{\cos x}$, $\csc x = \frac{1}{\sin x}$ and $\cot x = \frac{1}{\tan x}$. Two identities follow: $1 + \tan^2 x \equiv \sec^2 x$ and $1 + \cot^2 x \equiv \csc^2 x$. $\arcsin$, $\arccos$ and $\arctan$ give one angle in a restricted range.

1. Turn $\sec$, $\csc$ and $\cot$ into $\cos$, $\sin$ and $\tan$.
2. Use the identities to get one function.
3. Solve and find every angle in the interval.

Watch out $\sec x$ is $\frac{1}{\cos x}$, not $\cos^{-1} x$.