Remember that -1<sin(x)<1y=1/(2+sinx)
As 2+sin(x) is always positive, 1>1/(2+sin(x))>1/3
And you have the min & max
But -1>-pi/2 and 1<pi/2, and we know that sin is an increasing function in [-pi/2,pi/2]
So sin(-pi/2) < sin(-1) < sin(cos(x)) < sin(1) < sin(pi/2)
For the third one, it's basic if you use the condition of the first question.
For the fourth one, it's also the same property you'll have to use.