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.