-π/2 & lt； x+π/6 & lt； π/2

-2π/3 & lt； x & ltπ/3

I. e. that monotonically decrease interval of the function.

X=π/3 belongs to [0, π]

So the minimum value is 1.

When x=0 and y=2.

When x=π, y=4 is the maximum.