求y=2sinx(sinx+cosx)的单调区间

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求y=2sinx(sinx+cosx)的单调区间
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求y=2sinx(sinx+cosx)的单调区间
求y=2sinx(sinx+cosx)的单调区间

求y=2sinx(sinx+cosx)的单调区间
y=2sinx(sinx+cosx)=2(sinx)^2+2sinxcosx
=1-cos2x+sin2x
=√2sin(2x-π/4)+1
2kπ-π/2<2x-π/4<2kπ+π/2(k∈Z)时单调递增
2kπ+π/2<2x-π/4<2kπ+3π/2(k∈Z)时单调递减
所以单调增区间是(kπ-π/8,kπ+3π/8)(k∈Z)
单调减区间是(kπ+3π/8,kπ+7π/8)(k∈Z)