sinx cosx=cos2x

（Ⅰ）∵f（x）=sin2x+cos2x∴f(π4)＝sinπ2+cosπ2＝1（Ⅱ）f(α2)＝cosα+sinα＝22∴sin(α+π4)＝12，cos(α+π4)＝±32．sinα＝sin(α+

y=7-4sinxcosx+4cos2x-4cos4x=7-2sin2x+4cos2x（1-cos2x）=7-2sin2x+4cos2xsin2x=7-2sin2x+sin22x=（1-sin2x）2

派再问：求过程再答：再答：给好评再问：三角形3边ABC满足B^2=AC求f(B的取值范围。。)再答：先给好评，立马帮你解决再答：应该是abc吧？再问：嗯。再问：？

sin2x=2sinxcosxcos2x=(cosx)^2-(sinx)^2sin2x+sinxcosx-cos2x=3sinxcosx-(cosx)^2+(sinx)^2由于sinx-2cosx=0

y=√3cos2x+sin2x=√[1²+(√3)²]sin(2x+z)=2sin(2x+z)其中tanz=√3/1=√3所以最大=2,最小=-2T=2π/2=π

（Ⅰ）f（x）=32sin2x-（cos2xcosπ3-sin2xsinπ3）-cos2x+12=3sin2x-cos2x-12=2sin（2x-π6）-12，∴f（x）的最小正周期T=π．当2kπ-

sinx/cosx=tanx=2sinx=2cosx带入恒等式sin²x+cos²x=1cos²x=1/5sinxcosx=(2cosx)cosx=2cos²x

f(x)=(√3)sinxcosx+cos2x+1f(x)=(√3)(2sinxcosx)/2+cos2x+1f(x)=(√3/2)sin2x+cos2x+1f(x)=(√7/2)[(√3/2)(2/

f(x)=2√3sinxcosx-cos2x=√3sin2x-cos2x=2(sin2x*√3/2-cos2x*1/2)=2sin(2x-π/6)x=π/12;函数f(x)的图象可以由函数y(x)=2

（1）∵f（x）=3sinxcosx-cos2x+12=3sinxcosx-2cos2x−12=32sin2x-12cos2x=sin（2x-π6），∴T=2π2=π．（2）设由y=f（x）（0≤x≤

f(x)＝cos2x-sin2x+2√3sinxcosx＝cos2x-sin2x+√3sin2x＝cos2x+(-1+√3)sin2x＝√(5-2√3)sin(2x+φ)＝(√5-√3)si(2x+φ

分两部分求2sin2x=4sinxcosx注：sin2x=2sinxcosx=4sinxcosx/{(cosx)^2+(sinx)^2}注：{(cosx)^2+(sinx)^2=1=4tanx/{1+

tanx=3cosx^2=1/(1+tanx^2)=1/10sinxcosx+cos2x=tanx*cosx^2+2cosx^2-1=3/10+2/10-1=-1/2

f(x)=2sinxcosx+cos2x=sin2x+cos2x=√2sin(2x+π/4)2x+π/4=π/2+2kπ时f(x)有最大值f(x)=√2x=π/8+kπ2x+π/4=3π/2+2kπ时

f(x)=sin2x+cos2x=√2sin(2x+π/4)f(π/4)=√2sin(2*π/4+π/4)=√2*√2/2=10

f(x)=sin2x+cos2x=√2sin(2x+π/4)所以T=2π/2=π最大值=√2f(θ+π/8)=√2sin(2θ+π/4+π/4)=√2cos2θ=√2/3cos2θ=1/3θ锐角则si

f(x)=√3sinxcosx+cos2x+1=(√3/2)sin2x+cos2x+1=[(√7)/2][(√3/√7)sin2x+(2/√7)cos2x]+1=[(√7)/2]sin(2x+α)+1

cos2x-2根号3sinxcosx=cos2x-根号3（2sinxcosx）运用倍角公式得=cos2x-根号3sin2x运用辅助角公式得=-2sin(2x-六分之π)由ω=2,T=二派除以ω,所以周

解:原式=√3sin2x＋cos2x＋1=2(√3/2sin2x＋1/2cos2x＋1=2cos(2x-pai/3)＋1.

不对,因为f（x）=cos2x-2√3sinxcosx=cos2x-√3sin2x=2[sinπ/6cos2x-cosπ/6sin2x]=2sin(π/6-2x)左移5π/12,f（x）=2sin【π