How do you simply sec(-x)?
You probably meant "simplify".
The secant function is only the inverse of the cosine function.
Now, the cosine function is said to be an "even" function.
That is, if you put
I hope this helps!
Since secant is an even function f(-x)= f(x), so therefore to simplify it, it's just sec(x)
Sec and Cos are even functions, meaning they have y-axis symmetry
Tan, Cot, Sin, Csc are odd functions, meaning that they have origin symmetry and f(-x) in this case is equal to -f(x).