
HARD domain problem
What is the domain of the following vector?
f(t) = 6 sec ^ (2t) i + t/sqrt(t ^ 2  4) j
I know that a part of its domain is abs(t) > 2 but what about sec???
By the way, here's the domain my book gives but it doesn't make any sense to me.
"t" does NOT equal [pi(2n + 1)]/4 (equal sign crossed by a short line)
and...
abs(t) > 2
Cheers.

If $\displaystyle t=\frac{(2K+1)\pi}{4}$ then $\displaystyle \cos(2t)=0$ therefore $\displaystyle \sec(2t)$ is not defined.

I see. I must have had a mind block because that does make sense. :) Thank you.
But I'm kinda irritated because I find that it's very, very hard to determine an equation for that domain type................