计算:2cos(-660°)-sin630°/4cos1020°+2cos(-300°)
计算:2cos(-660°)-sin630°/4cos1020°+2cos(-300°)
cos^2x+cos^2(x+120°)+cos^2(x+240°)
【紧急求助】计算:cosα+cos(2π/3 +α)+cos(4π/3 +α)
计算值 COS(-2040°)
计算:cos(-150°)=
计算:(√3 tan12°-3)/sin12°(4cos^2 12°-2)
计算:tan12°-√3/[(4cos²12°-2)sin12°]
求证cos(720°+α)(2/cosα+tanα)(1/cosα-2tanα)=2cosα-3tanα
cos²α+cos²(120°-α)+cosαcos(120°-α)化简
化简cos^2A+cos^(120°+A)+cos^2(240°+A)这个怎么化简呢?
化简cosα+cos(120°-α)+cos(120+α)
计算:(1)根号2sin45°+cos²60°-根号3tan60°+sin30°·tan45°