cosx等于sin(x 2/π)

cos-x自己画个坐标就一目了然了

∵cos(A-B)=cosA*cosB+sinA*sinB∴逆用以上公式得sinx*sin(x+y)+cosx*cos(x+y)=cos[(x+y)-x]=cosy∴sinx*sin(x+y)+cos

∵f(x)=2sin(π-x)cosx=2sinxcosx=sin2x1、最小正周期T=2π/2=π.2、∵-π/6≤x≤π/2∴-π/3≤2x≤π,∴-√3/2≤f(x)≤1,∴最大值1,最小值-√

sin(x+y)sinx+cos(x+y)cosx=（sinxcosy+sinycosx）sinx+（cosxcosy-sinxsiny）cosx=（sinx)^2*cosy+(cosx)^2*cos

sin(x-3π/4)=sin[π-(π/4-x)]=sin(π/4-x)=-sin(x-π/4)sin(x-3π/4)cos(x-π/4)=-sin(x-π/4)cos(x-π/4)=-sin(2x

y=cosx•sin（x+π2）=12[sin（2x+π2）-sin（-π2）]=12cos2x+12∴T=2π2=π故答案为π再问：为什么cosx)^2=(cos2x+1)/2？看不太懂...

√2sin(x-π/4)=√2(sinxcosπ/4-cosxsinπ/4)=√2[(1/√2)sinx-(1/√2)cosx]=sinx-cosx

y=4sin的平方x+4cosx+5=4(1-cos的平方x)+4cosx+5=-4cos的平方x+4cosx+9=-4(cosx-1/2)^2+10-π/3小于等于x小于等于（2π）/3-1/2≤c

sin(πcosx)=cos(πsinx)sin(πcosx)=sin[π/2-(πsinx)]cosx=1/2-sinxsinx+cosx=1/21+2sinxcosx=1/43/4=sin2x2x

πcosx=-πsinx+π/2cosx+sinx=1/2sin(x+π/4)=1/2√2x+π/4=arcsin(1/2√2)+2kπ或x+π/4=π-arcsin(1/2√2)+2kπx=-π/4

sin(πcosx)=cos(πsinx)πcosx+πsinx=π/2cosx+sinx=1/2平方1+2sinxcosx=1/4sinxcosx=-3/8所以sinx=(1±√7)/4x=arcs

∵函数f（x）=2sin(x+π4)+2x2+x2x2+cosx=sinx+cosx+2x2+x2x2+cosx=1+sinx+x2x2+cosx．令g（x）=sinx+x2x2+cosx，则g（x）

(cosx)'=[sin(π/2-x)]‘=cos(π/2-x)*(π/2-x)'=sinx*(-1)=-sinx

1-cosx=1-cos(x/2+x/2)=1-cos²x/2+sin²x/2=2sin²x/2

当0≤x≤π时,-1≤cosx≤1,令t=cosx,此时对于sint来说,在[-1,1]内为单调递增,所以f(x)最大值为sin1,最小值为sin（-1）

sin(πcosx)=cos(πsinx)则πcosx=π/2-πsinx+2kπ或πcosx=π/2+πsinx+2kπ则cosx=1/2+2k-sinx或cosx=1/2+2k+sinx因为-1再

如图,因为cosx=a在[0,2pi]上的不相等的两个实数根x1 ,x2关于过图像顶点的直线对称,所以有x1+x2=2pi,所以有sin(x1+x2)=0

sin2atana=2sinacosa*sina/cosa=2sin²a√(1-cosx)=√[2sin²(x/2)]=√2|sin(x/2)|sinπ/10×cosπ/5=cos

f(x)=(sinx)^2+cosx=1-(cosx)^2+cosx=-(cosx)^2+cosx+1设t=cosx|x|≤π/4√2/2≤t≤1y=-t^2+t+1=-(t-1/2)^2+5/4在[

向量b＝（2cos,sinx)f(x)＝2cos^2x＋sinxcosx+1=1/2sin2x+cos2x+2=√5/2sin（2x+Φ）＋2这个函数的周期是π