Question

How do you evaluate `sec(2 arcsin(-1/3))`?

Answer 1

`9/7`

Explanation:

Let `a = arc sin (-1/3)`. Then,

`sin a = (-1/3)`.

So, `cos 2 a=1-2 sin^2 a= 1 - 2 (1/9)=7/9`

The given expression is `sec 2 a=1/(cos 2a) =9/7`..