tan a=2.tanx =3,a,x,为锐角那么a x=

再答：

tanx=tan(x/2+x/2)=(2tanx/2)/(1-(tanx/2)^2)=4/3所以tanx/2=-2或1/2

tan(π/4+A)=sin(π/4+A)/cos(π/4+A)=(sinπ/4*cosA+cosπ/4*sinA)/(cosπ/4*cosA-sinπ/4*sinA)=(tanπ/4*cosA+si

解析：已知π

解:因为tana/(tana-1)=-1,所以tana=1/2,所以[sin(PAI-a)＋3cos(PAI＋a)]/[sina＋cos(-a)]=(sina＋3cosa)/(sina＋cosa)=(

左边=sinx/cosx*sinx/(sinx/cosx-sinx)上下乘cosx=sin²x/(sinx-sinxcosx)=sinx/(1-cosx)上下乘1+cosx=(sinx+si

cot(45°+A）=1/tan(45°+A）=(1-tanA)/(1+tanA)=2+√3

结果:tana*tanb=1/2.过程也不复杂,把tana移项,然后展开tan(a+b),再全部通分,两边合并同类项.

tana+1/tana=3可化成sina/cosa+cosa/sina=3化简得sin^2a+cos^2a/sinacosa=3可得出sinacosa=1/3由此可得出sina+cosa=根号15/3

(tanA+tanB)/(1-tanA*tanB)=-1两边同乘以(1-tanA*tanB),等式两边就为(tanA+tanB)=-(1-tanA*tanB),“-“(1-tanA*tanB)注意这个

tanA=2tan(A/2)/[1-(tan(A/2))^2]-2/tanA=-2*[1-(tan(A/2))^2]/[2tan(A/2)]=[(tan(A/2))^2-1]/(tanA/2)tan(

证明：tan(a+b)=(tana+tanb)/(1-tana·tanb)∴tan(a+π/4)=[tana+tan(π/4)]/[1-tana·tan(π/4)]=(1+tana)/(1-tana)

tan(a/2)-1/(tana/2)=sin(a/2)/cos(a/2)-cos(a/2)/sin(a/2)通分=[sin²(a)-cos²(a/2)]/[sin(a/2)cos

tan3a=[3tana-(tana)^3]/[1-3(tana)^2]=1/tana,∴3(tana)^2-(tana)^4=1-3(tana)^2,∴(tana)^4-6(tana)^2+1=0,

f(x)=sin^2x+sinxcosx-sin^2x+cos^2x=sinxcosx+cos^2x=sin2x/2+(1+cos2x)/2=sin2x/2+cos2x/2+1/2(1)f(a)=si

,而sin^2a+cos^2a=1,得sin^2a=4/5f(x)=(1+1/tanx)sin^2-2sin(x+π/4)sin(x-π/4).=sinx(cosx+sinx)+2sin(x+π/4)

将函数f(X)=(1+1/tanx)sin^2x+msin(x+π/4)sin(x-π/4)化简得：=(1+cosx/sinx)*2sinxcosx+m(sinxcosπ/4+cosxsinπ/4)(

sin^2a*tana+cos^2a*1/tana+2sina*cosa=(1-cos^2a)*tana+(1-sin^2a)*1/tana+2sina*cosa=tana-sina*cosa+1/t

tan(45+A)=(tan45+tanA)/(1-tan45tanA)tan45=1tan(45+A)=(1+tanA)/(1-tanA)=1/(2+√3)=2-√3