定义域是R
y>=0
y^2=1+sinx+1-sinx+2√(1-sinx)(1+sinx)
=2+2√[1-(sinx)^2]
=2+2√(cosx)^2
=2+2|cosx|
0<=|cosx|<=1
0<=2|cosx|<=2
2<=2+2|cosx|<=4
2<=y^2<=4
y>=0
√2<=y<=2
值域[√2,2]