Question

When you're evaluating sec(arcsin 2/5), how would you know that it's in the first quadrant?

Answer 1

or does it even matter. ;c

Answer 2

It does not matter. In this question Drawing this would be helpful

To find arcsin(2/5) we need to find a number x such that sin(x)=2/5
So we draw the triangle with an angle x and 2 as our opposite side and 5 as hyp since sine= opp/hyp.
So since arcsin2/5 =x all we need to find is sec x which is the same as 1/cosx
I'm sure you can find cos given that diagram.

Answer 3

Yees, tysm C: