Question

What does sec pi/2 equal?

Answer 1

The secant function can't be evaluated in `pi/2`.

Explanation:

Just apply the definition and evaluate:

`sec(x)=1/cos(x)`

Thus,

`sec(pi/2)=1/cos(pi/2)`

But since `cos(pi/2)` is zero, this division is not legit.

We can calculate the limit, so see if it's positive or negative infinite. Since the cosine function is positive before `pi/2` and negative after, we will have that

`lim_{x\to (pi/2)^+} sec(x)=infty`, and

`lim_{x\to (pi/2)^-} sec(x)=-infty`