cos((-47/10)π)=cos(-4π-7π/10)=cos(-7π/10)=cos7π/10
cos((-44/9)π) =cos(-4π-8π/9)=cos(-8π/9)=cos8π/9
y=cosx在区间【0,π】上是减函数
所以 cos8π/9cos((-44/9)π)
tan((3/2)π-1)=cot1>0
tan((3/2)π+1)=-cot1tan((3/2)π+1)
比较大小1:cos((-47/10)π)与cos((-44/9)π) 2:tan((3/2)π-1)与tan((3/2)
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