已知函数f(x)=sin^x+根号3sinxcosx+2cos^x,x属于R
1个回答

1,f(x)=sin²x+√3sinxcosx+2cos²x

=1-cos²x+√3/2 sin2x+2cos²x

=cos²x+√3/2 sin2x+1

=(1+cos2x)/2+√3/2 sin2x+1

=1/2cos2x+√3/2 sin2x+3/2

=sin(2x+π/6)+3/2

所以函数f(x)是由y=sin2x的图像向左平移π/6个单位再向上平移3/2个单位得到的.

2,先求五个关键点:

函数的1/4周期是( 2π/2) *(1/4)=π/4

令2x+π/6=0得x=-π/12

-π/12+π/4=π/6

π/6+π/4=5π/12

5π/12+π/4=2π/3

2π/3+π/4=11π/12

∴五个关键点是(-π/12,3/2),(π/6,5/2),(5π/12,3/2),(2π/3,1/2),(11π/12,3/2)

请复核数字计算