(1)将函数f(x)的解析式化为f(x)=Asin(ωx+φ) 的形式,并指出它的最小正周期
(2)当x∈[- π/6,π/6]时,求f(x)的最小值和相应x的值
一道数学会考题:已知函数f(x)=sin(2x+π/3)+cos(2x-π/6)
答案:3 悬赏:20 手机版
解决时间 2021-12-26 15:07
- 提问者网友:我没有何以琛的痴心不悔
- 2021-12-25 19:14
最佳答案
- 五星知识达人网友:旧脸谱
- 2022-01-22 05:27
1)f(x)=sin(2x+π/3)+sin(π/2-2x+π/6)
=sin(2x+π/3)+sin(-2x+2π/3)
=sin(2x+π/3)+sin(2x+π/3)
=2sin(2x+π/3)
T=2π/2=π
2)-π/6=
0=<2x+π/3<=2π/3
最小值为2x+π/3=0时,f(x)=0
此时x=-π/6
=sin(2x+π/3)+sin(-2x+2π/3)
=sin(2x+π/3)+sin(2x+π/3)
=2sin(2x+π/3)
T=2π/2=π
2)-π/6=
最小值为2x+π/3=0时,f(x)=0
此时x=-π/6
全部回答
- 1楼网友:撞了怀
- 2022-01-22 06:51
(1)f(x)=sin2xcosπ/3+sinπ/3cos2x+cos2xcosπ/6+sin2xsinπ/6=sin2x+根号3cos2x=2sin(2x+π/3)
T=π
(2)当x∈[- π/6,π/6]时,2x+π/3∈[ 0,2π/3]所以当x=-π/6有最小值为2sin0=0
- 2楼网友:轻熟杀无赦
- 2022-01-22 06:00
f(x)=sin(2x+π/6)-cos(2x+π/3)+2cos²x
=根号下3sin2x/2+cos2x/2-cos2x/2+根号下3sin2x/2+2cos²x-1+1
=根号下3sin2x+cos2x+1
=2(根号下3sin2x/2+cos2x/2)+1
=2sin(2x+π/6)+1
f(π/12)=2sin(π/3)+1=根号下3+1
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