Question

If x is on quadrant 2 and tan x = a , then make another comparison of trigonometry (?)

Answer 1

`tan x = a`

That's a right triangle with opposite `a` and adjacent `1`.

`cos a = -1/sqrt{a^2 + 1}`

`sin a = a/sqrt{a^2 + 1}`

The second quadrant has a negative cosine and a positive sine.