Q: Which expression completes the fundamental trigonometric identity ? sec(-x)
A. -sec x
B. sec x
C. cos x
D. -cos x
A: This is just a trig identity that should be memorized. For a list of all of the trig identities, you can go to:
Or, you can find them listed on many other websites (or even in your text book probably).
You will find that: sec(-x) = sec(x)
So, the correct answer is B.