Question

比较大小 sin3π/5______cosπ/5

Answer 1

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y=sin(x-6分之π),x∈【0,π】x-π/6∈【-π/6,5π/6】利用正弦函数的图像x-π/6=-π/6时,y有最小值-1/2x-π/6=5π/6时,y有最大值1/2∴y∈【-1/2,1/2】