a∈(0,π/2) 则sin三次方a/cosa+cos三次方a/sina最小值

问题描述:

a∈(0,π/2) 则sin三次方a/cosa+cos三次方a/sina最小值

a∈(0,π/2)
sina*cosa=(1/2)sin2a∈(0,1/2]
则0为什么t∈(0,1/2]t=(1/2)sin2a0