问题标题：
化简sin(kπ+π/3)cos(3kπ+2π/3)(k属于Z)
问题描述：
化简sin(kπ+π/3)cos(3kπ+2π/3)(k属于Z)
李书训回答：
sin(kπ+π/3)cos(3kπ+2π/3)
=sin(kπ+π/3)cos(kπ+2π/3)
={sin[(kπ+π/3)+(kπ+2π/3)]+sin[(kπ+π/3)-(kπ+2π/3)]}/2
=[sin(2kπ+π)+sin(-π/3)]/2
=[sin(π)-sin(π/3)]/2
=－√3/4
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