nynw.net
当前位置:首页 >> 已知向量m=(根号3sinx/4,1),向量n=(Cosx/4,Cos^2... >>

已知向量m=(根号3sinx/4,1),向量n=(Cosx/4,Cos^2...

、先将f(x)=m*n化成一个函数式子,f(x)=m*n=√3sinxcosx/16+cosx/4,根据二倍角公式,等于三十二分之根号三倍的sin2x加上八分之cos2x加上1,。并进行提取公因式得到十六分之一倍的括号里二分之根号三倍的sin2x加上二分之cos2x括号结束再加上一,...

f(x)=m*n=√3sinx/4cosx/4+cos²x/4 =√3/2sinx/2+1/2cosx/2+1/2 =cos(x/2-π/3)+1/2 f(a)=3/2, cos(a/2-π/3)+1/2=2/3 cos(a/2-π/3)=1 cos(2π/3-a)=cos(a-2π/3) =2cos^2(a/2-π/3)-1 =2*1^2-1 =1

m*n =√3sin(x/4)cos(x/4) cos²(x/4) =(√3/2)sin(x/2) ( cos(x/2) 1) /2 =((√3/2)sin(x/2) (1/2)cosx/2) 1/2 =cos(π/3 -x/2) 1/2 1)∵m*n=1 ∴f(x)=cos(π/3-x/2) 1/2=1 cos(π/3 -x/2) = 1/2 cos(2π/3 -x) =2cos²(π/3-x/2)-1=1/2

m=(√3sinx/4,1),n=(cosx/4,cos2x/4) f(x)=m*n=√3sinx/4*cosx/4+cos2x/4 =(√3/2)*2sinx/4*cosx/4+(1/2)(1+cosx/2) =cos(π/6)sinx/2+sin(π/6)cosx/2+1/2 =sin(x/2+π/6)+1/2 f(x)=1 sin(x/2+π/6)=1/2 cos(x+π/3)=cos[2(x/2+π/6)]=1-2(sin(x/2+π/6)...

推荐大家一个很好的手机软件,大家如果觉得非常好的话就给个好评吧! 应用下载网址http://a.mizhuan.me/r/241d282.apk

M是SIN四分之X吧? (1)由M·N=1得 √3/2sinx/2+1/2cosx/2+1/2=1 化简 sin(x/2+派/6)=1/2 所以 cos(pi/3-x/2)=1/2 cos(2pi/3-x0=2cos^2(pi/3-x/2)-1=-1/2 (2)易得f(x)=sin(x/2+pi/6)+1/2 (2a-c)cosB=bcosC由正弦定理得2sinAcosB=sinBcosC+sinCcosB ...

(1)∵f(x)=3sinx?cosx-4cos 2 x= 3 2 sin2x-2(cos2x+1)= 3 2 sin2x-2cos2x-2,∴f( π 4 )= 3 2 -2=- 1 2 ;(2)∵f(x)= 3 2 sin2x-2cos2x-2= ( 3 2 ) 2 + (-2) 2 sin(2x+φ)-2= 5 2 sin(2x+φ)-2,(tanφ= 4 3 ),又x∈R,∴- 9 2 ≤f...

(1)∵f(x)=3sinx?cosx-4cos2x=32sin2x-2(cos2x+1)=32sin2x-2cos2x-2,∴f(π4)=32-2=-12;(2)∵f(x)=32sin2x-2cos2x-2=(32)2+(?2)2sin(2x+φ)-2=52sin(2x+φ)-2,(tanφ=43),又x∈R,∴-92≤f(x)≤12;又m≤f(x)≤M,M-m的最小值为:5.

(1)∵a=(2sin(π/4-x),cosx) b=(cos(π/4-x),2√3sinx) ∴f(x)=2sin(π/4-x) * cos(π/4-x) + cosx * 2√3sinx =sin[2(π/4-x)]+2√3sinxcosx =sin(π/2-2x) + 2√3sinxcosx =cos2x + √3sin2x =2sin(2x+π/6) ∵T=2π / |w| ∴T=2π / 2=π ∵sin(2x+π/6)∈[-1,1] ...

网站首页 | 网站地图
All rights reserved Powered by www.nynw.net
copyright ©right 2010-2021。
内容来自网络,如有侵犯请联系客服。zhit325@qq.com