已知x=2cosx,sinx,b=根号3
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F(x)=m.n=2根号3sinxcosx+cos^2x-sin^2x=根号3sin2x+cos2x=2sin(2x+π/6)
f(x)=sinxcosx+cos²x-1/2=1/2*sin2x+1/2*(1+cos2x)-1/2=1/2*sin2x+1/2*cos2x=√2/2*(√2/2*sin2x+√2/2*c
f(x)=2sinx(sinX+cosX)=2sinxsinx+2sinxcosx=1-cos2x+sin2x=√2sin(2x-π/4)+1所以f(x)的最小正周期=2π/2=π最大值=1+√2
f(x)=a*b=2sinxcosx+(sinx+cosx)(cosx-sinx)=sin2x+cos2x=√2sin(2x+π/4)1)当x∈[0,π/2]时2x+π/4∈[π/4,π/4+π]当2
f(x)=sin2x-2cosx^2-1=sin2x-cos2x-2=根号2sin(2x-45)-2最小正周期为派最大值为根号2-2将所有点纵坐标变为2倍,向左平移四分之派个单位,将所有点的横坐标变为
f(x)=2sinx^2+sinx*cosx+cosx^2,x∈R=1-cos(2x)+1/2sin(2x)+(1+cos(2x))/2=√2/2sin(2x-π/4)+3/2(1)f(π/12)=(
1.f(x)=1/2cos2x+√3/2sin2x+cos^2x-sin^2x=3/2cos2x+√3/2sin2x=√3sin(2x+π/3)2.x属于【-π/12,π/2】,所以2x+π/3属于【
这类题全都是要把表达式用倍角公式等化简成y=Asin(ωx+φ)形式.f(x)=2cosxsinx-2cosxcosx+1=sin2x-cos2x=√2*sin(2x-π/4)T=π,最大值√2,最小
提示:sin45°等于cos45°【很重要】如sin2x-cos2x就可以写成sin2x*cos45°-sin45°cos2x;F(X)=sinX*sinX-sinxcosx(sin2x=2sinxc
(sinx+cosx)/(sinx-cosx)=3sinx+cosx=3sinx-3cosxsinx=2cosxtanx=sinx/cosx=2sinx=2cosx带入恒等式sin²x+co
因为sinx+cosx/sinx-cosx=3,所以sinx+cosx=3sinx-3cosxsinx=2cosx即tanx=sinx/cosx=2又sin²x+cos²x=15c
∵(sinx+cosx)/(sinx-cosx)=3==>(sinx/cosx+1)/(sinx/cosx-1)=3==>(tanx+1)/(tanx-1)=3==>tanx+1=3(tanx-1)=
f(x)=(1-sinx+cosx)/(1-sinx-cosx)+(1-sinx-cosx)/(1-sinx+cosx)=[(1-sinx+cosx)^2+(1-sinx-cosx)^2]/(1-si
f(x)=2cosx(sinx-cosx)+2=2cosx*sinx-2(cosx)^2+2=sin2x-[2(cosx)^2-1]+1=sin2x-cos2x+1=根号(2)*sin(2x-π/4)
解析:∵a*b=(cosx+sinx,sinx)*(cosx-sinx,2cosx)=(cosx+sinx)(cosx-sinx)+2sinxcosx=[(cosx)^2-(sinx)^2]+2sin
f(x)=2sinx(sinx+cosx) =2sin²x+2sinxcosx =2sin²x-1+2sinxcosx+1&
sinx+cosx=1/2平方得:1+2sinxcosx=1/4sinxcosx=-3/8
(sinx+cosx)/(cosx-sinx)=2分子分母同时除以cosx∴(tanx+1)/(1-tanx)=2∴tanx+1=2-2tanx∴3tanx=1∴tanx=1/3∴2sin²