求cos5π/12sinπ/12
问题描述：
求cos5π/12sinπ/12
答
∵Cos5π/12=Sin(π/2-5π/12 )
=Sinπ/12
∴cos5π/12sinπ/12 =S²inπ/12
=（1—Cosπ/6)/2=(2－√3)／4