What does sec pi/2 equal?

1 Answer
Oct 16, 2015

The secant function can't be evaluated in pi/2π2.

Explanation:

Just apply the definition and evaluate:

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

Thus,

sec(pi/2)=1/cos(pi/2)sec(π2)=1cos(π2)

But since cos(pi/2)cos(π2) 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/2π2 and negative after, we will have that

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

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