I have nearly no clue on how to do these kind of problems, I somewhat understand how to move the values by pi and pi/2 (kinda off sometimes) and I do know that cosine is x and sine is y

One question I want to ask first is, when adding or subtracting by pi/2, do the sine and cosine values flip and become negative or does that happen when adding pi or ?

1) Suppose cos(5) = 0.28 and sin (5) = -0.96, find an angle alpha such that cos(alpha) = 0.28 and sin(alpha) = 0.96 without using a calculator

2) If cos(t) = -3/5 and pi< t <3pi/2, find tan(t) without a calculator

3) Find a value of alpha where -3pi< alpha < -2pi

Any help is appreciated as always, I'll be sure to give you a thanks for your input