问题描述: 设角=35/6兀,则2sin(兀+a)cos(兀-a)-cos(兀+a)/1+sin^2a+sin(兀-a)-cos^2(兀+a)值= 1个回答 分类:数学 2014-11-06 问题解答: 我来补答 a=35π/6a=6π-π/6a=-π/62sin(π+a)cos(π-a)-cos(π+a)/[1+sin^2a+sin(π-a)-cos^2(π+a)]=2sin(π-π/6)cos(π+π/6)-cos(π-π/6)/[1+sin^2(-π/6)+sin(π+π/6)-cos^2(π-π/6)]=2sinπ/6(-cosπ/6)-(-cosπ/6)/[1+sin^2(π/6)+(-sinπ/6)-(-cosπ/6)^2]=-2sinπ/[6cosπ/6+cosπ/6/2sin^2(π/6)-sinπ/6]=-cosπ/6(2sinπ/6-1)/[sinπ/6(2sinπ/6-1)]=-cosπ/6/sinπ/6=-(√3/2)/(1/2)=-√3 展开全文阅读