Hello,

Remember that -1y=1/(2+sinx)<sin(x)<1

So 1<2+sin(x)<3

As 2+sin(x) is always positive, 1>1/(2+sin(x))>1/3

And you have the min & max

-1y=sin(cosx)<cos(x)<1

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.