化简cos(π/3-θ)cosθcos(π/3+θ)

问题描述:

化简cos(π/3-θ)cosθcos(π/3+θ)

cos(π/3-θ)cosθcos(π/3+θ)=[cos(π/3-θ+π/3+θ)+cos(π/3-θ-π/3-θ]cosθ/2=(cosθ)^3-3cosθ/4