已知函数f(x)=sin눀x+根号3sinxcosx+2cos눀x,x∈R

2024-12-21 18:37:13
推荐回答(3个)
回答1:

f(x)=sin²x+根号3sinxcosx+2cos²x
=1/2(2cos²x-1)+1/2+(sin²x+cos²x)+√3/2(2sinxcosx)
=1/2cos2x+√3/2sin2x+3/2
=sin(2x+π/6)+3/2
所以可得:最小正周期T=2π/2=π
单调增区间为:[kπ-π/3,kπ+π/6] (注:k为任意整数)

x∈【0,π/2】时求函数的值域
当x=π/6时有最大值为:5/2
当x=π/2时有最小值为:1
所以它在此区间上的值域为[1,5/2]

x∈【0,π/2】时求函数的单调递增区间
在[0,π/6] 上单调递增,
在[π/6,π/2] 上单调递减

回答2:

f(x)=(1-cos2x)/2+√3/2sin2x+1+cos2x
=√3/2sin2x+1/2cos2x+3/2
=sin(2x+π/6)+3/2
的最小正周期 T=2π/2=π
2kπ-π/2<=2x+π/6<=2kπ+π/2
kπ-π/3<=x<=kπ+π/6
单调地增区间 [kπ-π/3,kπ+π/6] k∈Z

x∈【0,π/2】
2x+π/6∈【π/6,5π/6】
函数的值域 [2,9/2]
函数的单调递增区间 [0,π/6]

回答3:

f(x)=sin^2x+√3sinxcosx+2cos^2x
=1+1/2+1/2*cos2x+√3/2*sin2x
=3/2+sin(2x+π/6)
(1)f(x)的最小正周期π
单调递增区间 2kπ-2π/2<=2x+π/6<=2kπ+π/2
即x属于[kπ-π/3,kπ+π/6]
(2)
x∈【0,π/2】时求函数的值域
2x+π/6属于[π/2,7π/6]
sin(2x+π/6)属于[-1/2,1]
f(x)属于[1,5/2]
(3)
f(x)单调递增区间为[kπ-π/3,kπ+π/6]
x的定义域为[0,π/2]
令k=0,则可得f(x)递增区间为[0,π/6]