若cos(5π/12＋θ)=1/7,则sin(π/12－θ)

若cos(5π/12＋θ)=1/7,则sin(π/12－θ) 若sinθ-cosθ=1/5,则cosθ乘以sinθ= 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) tanθ/(1+〖tan〗^2 θ)≡sinθcosθ(1-(〖tan〗^(2 ) 60)/sin30)〖cos〗^245sinθ=7/25 find the value of 3tanθ-1/cosθ by using 勾股定理(tanθ/cosθ+sinθ/(〖cos〗^2 θ ))×〖cos〗^2θCos(40-3θ)=sin(7θ+2)If tanA=5/3 find the value of 4s cos(2π/7)+cos(4π/7)+cos(6π/7)= -1/2.证明[cos(2π/7)]^2+[cos(4π/7)]^2+[cos(6π/7)]^2=5/4 cos(2π/7)+cos(4π/7)+cos(6π/7)= -1/2.证明[cos(2π/7)]^2+[cos(4π/7)]^2+[cos(6π/7)]^2=5/4 若sinθ+sin^2θ=1,则cos^2θ+cos^4θ+cos^6θ 若3cos(∏/2-θ)+cos(∏+θ)=0,则cos²θ+1/2sin2θ=? 若f(cosθ)=sin^2-3cosθ,则f(2cos π/3 )=_____ 若tanθ=1/2则(cosθ+sinθ/cosθ-sinθ),1-sinθcosθ+2cos^2θ= 如果|cosθ|=1/5,7π/2 若sin（θ-π）=2cos（2π-θ）求（1）sinθ+5cosθ/sinθ-3cosθ (2)sinθcosθ的值 若cos(π/4+θ)cos(π/4-θ)=1/4,则sin4θ+cos4θ等于 方程组：sin θ ×S=1/2gt² cos θ×S=Vt cos(π/12)cos(5π/12)= 若cos(α+π/3)=1/7,α∈（0,π/2）,则cosα=? cos^2 π/8+cos ^2 3π/8+ cos^2 5π/8+cos^2 7π/8=? 设α为锐角 若cos (α+π/3)=1/5则cos(α-π/6)=