Answer:
+- 5/3
Explanation:
When we construct a right triangle with legs with length 3 and 4. The hypoteneuse must 5. Since tan(x) = opp/adj = 4/3 and sec(x) = hyp/adj,
We get the answer to be 5/3. Now there is a +- there because if we use the unit circle, if we take the point (-3, -4), we get tan(x) = (-4/-3) = 4/3. However, the hypoteneuse for sec(x) is always positive so sec(x) = 5/-3 = -5/3.
That is why there are two solutions, one with the terminal arm in Q3 and one in Q1. But that's the explanation using the unit circle.