Question

How do you evaluate `sec(-pi)`?

Answer 1

`sec(-pi)=1/cos(-pi)`

Explanation:

The `cos` function is an even function, and that means that `cos(-x)=cos x`, for all values of `x`. In particular `cos(-pi)=cos pi = -1`. Then, since `sec (-pi) = 1/cos(-pi)=1/(-1)=-1`