（1) f(t)=√[(1-t)/(1+t)]
f(sinx)=√[(1-sinx)/(1+sinx)]
f(cosx)=√[(1-cosx)/(1+cosx)]
g(x)=cosx*f(sinx)+sinx*f(cosx)
=cosx*√[(1-sinx)/(1+sinx)]+sinx*√[(1-cosx)/(1+cosx)]
=√[((cosx）^2*(1-sinx))/(1+sinx)]+
√[((sinx）^2*(1-cosx))/(1+cosx)]
=√[((1-(sinx)^2)*(1-sinx))/(1+sinx)]+
√[((1-(cosx)^2)*(1-cosx))/(1+cosx)]
=√[((1+sinx)*(1-sinx)*(1-sinx))/(1+sinx)]+
√[((1+cosx)*(1-cosx)*(1-cosx))/(1+cosx)]
=√[(1-sinx)^2]+√[(1-cosx)^2]
=1-sinx+1-cosx
A>0,w>0,a∈【0,2π】
g(x)=2-sinx-cosx
=√2sin(x-3π/4)+2
（2）由-π/2 +2kπ< x-3π/4