已知0已知0<α<π/2,tan(α+π/4)=3+2根号2,则(1-cos2α)/sin2α=
已知0tan(α+π/4)=(1+tana)/(1-tana)=3+2√2tana=√2/2(1-cos2α)/sin2α=(1-(1-2sin^2a))/2sinacosa=sins/cosa=tana=√2/2