sin(π/2+θ)+cos(π/2-θ)=-1/5sin(π/2)cos(θ)+cos(π/2)sin(θ)+cos(π/2)cos(θ)+sin(π/2)sin(θ)=-1/5cos(θ)+sin(θ)=-1/5(1)(cosθ+sinθ)^2=1/251+2sinθcosθ=1/251-2sinθcosθ=49/25(sinθ-cosθ)^2=49/25sinθ-cosθ=±7/5(2)联立(1)(2)sinθ=-3/5,cosθ=4/5(舍去)或sinθ=4/5,cosθ=-3/5tanθ=sinθ/cosθ=-4/3望采纳追问：sin(π/2+θ)+cos(π/2-θ)=-1/5sin(π/2)cos(θ)+cos(π/2)sin(θ)+cos(π/2)cos(θ)+sin(π/2)sin(θ)=-1/5是怎么算的回答：两角和公式追问：我高一,没学了,有没有别的算法回答：没有.两角和是课本最基础的公式.高一一般都教完了追问：哦,那sin(π/2)cos(θ)+cos(π/2)sin(θ)+cos(π/2)cos(θ)+sin(π/2)sin(θ)=-1/5cos(θ)+sin(θ)=-1/5,这一步怎么算出来的回答：cos(π/2)=0sin(π/2)=1代进去啊.真不知道你怎么学的