hi guys , i am a high school student , and i have a trigonometry test tomorrow . i would appreciate every help from you.

for now i can't solve these trigonometry equations.

they are mashing up my mind

1) sin^{2}x + sinx * cosx = 1

2)1+cosx + cos(x/2) =0

3) 1 + cos(π +x ) + cos(π/2 + x/2) =0