cos(75°+α)=1/3 则cos(150°-α)等于几
cos(75°+α)=1/3 则cos(150°-α)等于几.急……
若cos(α+β)cos(α-β)=1/3 则cos²α-sin²β等于
已知cos(30°+α)=根号3/3,则cos(150°-α)等于
已知cos(75°+α)=1/3,则cos(150°-α)的值是多少?
求证cos(720°+α)(2/cosα+tanα)(1/cosα-2tanα)=2cosα-3tanα
cos(75°+α)=13
已知cosα=1/3,α属于(π,2π),则cosπ/2等于
若sinα-sinβ=1-根号三/2 cosα-cosβ=-1/2 则 cos(α-β)等于
cos(75°-α)=1/3,α是第三象限角,则cos(15°-α)+sin(α-15°)的值
cos²α+cos²(120°-α)+cosαcos(120°-α)化简
化简cosα+cos(120°-α)+cos(120+α)
已知cos(75°+α)=13,则cos(30°-2α)的值为 ___ .