Question

How do you evaluate `sec(arctan 2)`?

Answer 1

`+-sqrt 5`

Explanation:

Let a = arc tan 2. Then, tan a = 2 > 0. a is in either the 1st quadrant or the 3rd.

So, the given expression `sec a =+-sqrt 5`,

using `sec a =+-sqrt(1+tan^2 a)`..