作业帮 > 数学 > 作业

f(x)=sin(2x+π/6)+cos(2x-5π/3)+sin2x 1.求f(x)的最小正周期和单调区间

来源:学生作业帮 编辑:作业帮 分类:数学作业 时间:2024/07/15 05:24:49
f(x)=sin(2x+π/6)+cos(2x-5π/3)+sin2x 1.求f(x)的最小正周期和单调区间
2.若三角形ABC中 f(A/2)=根号2 a=2 b=根号6 求角C
(1)
f(x)=sin(2x+π/6)+cos(2x-5π/3)+sin2x
=sin2xcosπ/6+cos2xsinπ/6+cos2xcos5π/3+sin2xsin5π/3+sin2x
=√3/2sin2x+1/2cos2x+1/2cos2x-√3/2sin2x+sin2x
=sin2x+cos2x
=√2(√2/2sin2x+√2/2cos2x)
=√2sin(2x+π/4)
f(x)最小正周期T=2π/2=π
(2)
f(A/2)=√2
即sin(A+π/4)=1
∵π/4