Compound Angles or Double Angles?

Hi, I am stuck these types of questions and I just can't make any sense of them.

Do I apply compound angles or double angles or the simple trigno functions?

Kindly show me a few steps and I will take it from there.

Q) Find all the angles between 0 and 360 which satisfy the following equations:

1) $\displaystyle 2+sinycosy=2sin^2y$

2) $\displaystyle 2tan2x+sec40=1$

3) $\displaystyle 1+2sin(3z/2+75)=0$

Another question is that when they say sin40 or sin10+40, the 40,10 and 40 are all angles right, even if they don't write the degree sign on them?

Thanks!