cos(x+27°)cos(18°-x)-sin(18°-x)sin(x+27°)=cos(x+27°)cos(18°-x)+cos[90°-(60°-x)]sin(x-18°)原本是-sin(18°-x)负号怎么变成的+cos[90°-(60°-x)] cos前的负号
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cos(x+27°)cos(18°-x)-sin(18°-x)sin(x+27°)=cos(x+27°)cos(18°-x)+cos[90°-(60°-x)]sin(x-18°)原本是-sin(18°
cos(x+27°)cos(18°-x)-sin(18°-x)sin(x+27°)=cos(x+27°)cos(18°-x)+cos[90°-(60°-x)]sin(x-18°)原本是-sin(18°-x)负号怎么变成的+cos[90°-(60°-x)] cos前的负号
cos(x+27°)cos(18°-x)-sin(18°-x)sin(x+27°)=cos(x+27°)cos(18°-x)+cos[90°-(60°-x)]sin(x-18°)
原本是-sin(18°-x)负号怎么变成的+cos[90°-(60°-x)] cos前的负号
cos(x+27°)cos(18°-x)-sin(18°-x)sin(x+27°)=cos(x+27°)cos(18°-x)+cos[90°-(60°-x)]sin(x-18°)原本是-sin(18°-x)负号怎么变成的+cos[90°-(60°-x)] cos前的负号
这是三角函数的公式,cos cos-sin sin=cos(a+b)
所以,原式=cos(x+27°+18°-x)=cos45°=根号2/2
cos(x+27°)cos(18°-x)-sin(18°-x)sin(x+27°)=cos(x+27°)cos(18°-x)+cos[90°-(60°-x)]sin(x-18°)原本是-sin(18°-x)负号怎么变成的+cos[90°-(60°-x)] cos前的负号
数学、急cos(x+27°)cos(18°-x)-sin(18°-x)sin(x+27°)等于多少
sin(33°-x)cos(27°+x)+cos(33°-x)sin(27°+x)
cos(25°+x)cos(20°-x)-cos(65°-x)sin(20°-x)
cosx+cos(120°-x)+cos(120°+x)
cos^2x+cos^2(x+120°)+cos^2(x+240°)
cos x
cos x
化简cos(15°-x)-根号3cos(15°+x)+cos(45°+x)cos(15°-x)-根号3cos(15°+x)+cos(45°+x)=cos(15°-x)-根号3cos(15°+x)+cos(30°+15°+x)=cos(15°-x)-根号3cos(15°+x)+cos30cos(15+x)-sin30sin(15+x)=cos(15°-x)-二分之根号3cos(15°+x)-sin30sin
sin(65°-x)cos(x-20°)+cos(65°-x)cos(110°-x)=?
求cos(20°+x)cos(25°-x)-cos(70°-x)sin(155°+x)
求值:cos(x+27°)cos(x-18°)+sin(x+27°)sin(x-18°) 急救急救!
若cos(x-40°)=cos(x+20°)+cos(x-20°),则tanx的值______.
cos(27°+x)sin(57°+x)-sin(207°+x)sin(327°+x)
为什么cos(20°+x) = sin(70°-x)cos(25°-x) = -cos(155°+x)?这两步没怎么看懂.cos(20+x)cos(25-x)-sin(20-x)sin(25-x)cos(20+x)cos(25-x)-sin(20+x)sin(25-x)20,25都是度数
化简cosx-根号3cos(30°+x)+cos(x+60°)
化简cosx-√3 cos(30°+x)+cos(x+60°)
f(x)=2(cosx)^3+sin(360°-x)^2-cos(180°-x)-3/2+2cos(180°+x)+cos(-x)求f(π/3)