若cos(π/4+θ)cos(π/4-θ)=1/4,则sin4θ+cos4θ等于

化简cosθ+cos(θ+2π/3)+cos(θ+4π/3) 若cos(π/4-θ)cos(π/4+θ)=√2/6,且0 cos(θ+π/4)怎么算 计算：cos（π/5)+cos（2π/5)+cos(3π/5)+cos(4π/5) cos(π/17)*cos(2π/17)*cos(4π/17)*cos(8π/17) 求值:cos(π/11)cos(2π/11)cos(3π/11)cos(4π/11)cos(5π/11) 求值：cos(π/11)-cos(2π/11)+cos(3π/11)-cos(4π/11)+cos(5π/11) cos(π/11)cos(2π/11)cos(3π/11)cos(4π/11)cos(5π/11) cosπ/4cosθ-sin3π/4sinθ=0,求θ 化简sinθ+cos(θ+2π/3)+cos(θ+4π/3) 已知tan(θ+π/4)=-2,求cosθ平方+sinθcosθ-1 COSθ-SINθ=√2COS(θ+π/4) 0 已知cos(π/2+θ)=1/2,求cos（3π+θ）/cosθ（cos（π+θ）-1） + cos（θ-4π）/cos（θ+2π）cos（3π+θ）+cos（-θ）求值~ 若cos(π/4+θ)cos(π/4-θ)=1/4,则sin4θ+cos4θ等于 已知sinθsinβ=-4/7,则cosθcosβ∈已知tan(π-θ)=3,求下式的值 (5xin^3θ+cosθ)/(2cos^3θ+sin^2θcosθ) 若 sinθ ·cosθ=1/8,求 sinθ +cosθ?怎样用单位圆确定 sinθ 和cosθ大若 sinθ ·cosθ=1/8,求 sinθ +cosθ?怎样用单位圆确定 sinθ 和cosθ谁大谁小?θ属于（π/4，π/2），关键是怎样用单位圆比较大小 1+cos(2θ)+cos(4θ)+cos(6θ)=4cosθcos(2θ)cos(3θ)证明相等. cos(θ-π/2)等于cos(π/2-θ)