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三角函数的最值集合
f(x)=[1+sinx-2sin²(π/4-x/2)]/4*(sinx/2)【这整个式子再加上】√3(sinx/2)的最大值及取最大值是相应的x集合.
人气:175 ℃ 时间:2020-05-17 08:05:14
解答
f(x)=[1+sinx-2sin²(π/4-x/2)]/4*(sinx/2)+√3(sinx/2)
=[1+sinx-1+cos(π/2-x)]/4(sinx/2)+√3(sinx/2)
=sinx/2sin(x/2)+√3(sinx/2)
=2sin(x/2)cos(x/2)/2sin(x/2)+√3(sinx/2)
=cos(x/2)+√3(sinx/2)
=2sin(x/2+π/6)
当(x/2+π/6)∈{2kπ+π/2},即x∈{4kπ+2π/3}时,得最大值2
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