tanx等于2,则sinxcosx等于
来源:学生作业帮助网 编辑:作业帮 时间:2024/07/14 00:16:35
(sinx/cosx+cosx/sinx)*cos2x=(1/cosx*sinx)*cos2x=1/2*cos2x/sin2x=1/2*cot2x
sin2x+1=2tanx/(1+tan^2x)+1=4/5+1=9/5
cos^2(x/2)=sinxcos^2(x/2)=2sinx/2cosx/2cosx/2(cosx/2-2sinx/2)=0cosx/2不为0cosx/2-2sinx/2=0tanx/2=1/2再问
1/2把sinx变成2sin(x/2)cos(x/2)然后左右消去一个cos(x/2),然后我觉得你应该懂了.再答:sinx=2sin(x/2)cos(x/2)cos²(x/2)=cos(x
tanx=tan(x/2+x/2)=(2tanx/2)/(1-(tanx/2)^2)=4/3所以tanx/2=-2或1/2
tanX+tanX=2tanXtanX*tanX=tan^2X
sinx=2cosx,sinx^2+(1/2sinx)^2=1,得sinx^2=4/5,sin2x=2sinxcosx=sinx^2=4/5希望采纳
先将括号里的化成sin和cos,通分,得:原式=(sin^2X+cos^2X)/(sinXcosX)•cos^2X=1/(sinX•cosX)•cos^2X=cos
cos(2x+π)=-cos2x=-(1-tanx*tanx)/(1+tanx*tanx)=3/5采纳哦
f(tanx)=sinxcosx=½·sin2x=½·2tanx/(1+tan²x)=tanx/(1+tan²x)令tanx=-2,代入上式得:f(-2)=-2
tanx=3则:sinx/cosx=3sinx=3cosxsin2x/cos²x=2sinxcosx/cos²x=6cos²x/cos²x=6
如图所示,可以再追问
sinx/cosx=tanx=2sinx=2cosxsin²x=4cos²x因为sin²x+cos²x=1所以cos²x=1/5sin2x=2sinx
上下除以cosx因为sinx/cosx=tanx所以原式=(tanx+1)/(tanx-1)=3
(1+sinx+cosx)/(1+sinx-cosx)=[2sin(x/2)cos(x/2)+2cos(x/2)cos(x/2)]/2sin(x/2)cos(x/2)+2sin(x/2)sin(x/2
sin(3/2π-2x)=3/5cos(2x)=-3/52cosx^2-1=-3/5cosx=+/-根号5/5tanx=+/-2
当x≠kπ±π/2时,tanx=sinx/cosx当x=kπ±π/2时,tanx无意义(k∈Z)
2cos²x+sin2x=(2cos²x+2sinxcosx)/(sin²x+cos²x)分子分母同除以cos²x=(2+2tanx)/(1+tan&
对边除以邻边