2除以sin2θ+cos(π+θ)除以cos(π除以2-θ)=2/sin2θ+cos(π+θ)/cos(π/2-θ)=2/sin2θ-cosθ/cos(π/2-θ)=2/sin2θ-cosθ/sinθ=2/sin2θ-2cosθcosθ/2sinθcosθ=2/sin2θ-2cos^2θ/sin2θ=(2-2cos^2θ)/sin2...