Find all values of x for which the following is true. $\sec x = -1$
a) π + 2kπ b) (π/4) + 2kπ c) 2kπ d) (π/2) + kπ e) -(π/3) + 2kπ
I know that $\sec \theta =\frac 1 {\cos \theta}$. I don't know what to do after that. I think the unit circle is involved somehow.
This is for my online trigonometry class, it's a homework problem and I can't figure it out. Any help is much appreciated.
$\sec x=-1\iff\cos x=-1\iff x\equiv \pi\mod2\pi$.