已知sin(π-θ)-cos(π+θ)=√2/3,其中π/2＜θ＜π,求下列各式的值：（1）sinθ-cosθ；（2）sin³（π/2-θ）+cos³(π/2+θ) （1）sin(π-θ)-cos(π+θ)=√2/3sinθ+cosθ=√2/3(sinθ+cosθ)²=2/9...