已知函数f(x)=sin(x+∏／6)+sin(x-∏／6)=cosxa+a（a∈R,a是常数)

题目应该是"f(x)=sin(x+∏／6)+sin(x-∏／6)+cosx+a"吧?f(x)=sin(x+∏／6)+sin(x-∏／6))+cosx+a````=sinxcos∏／6+cosxsin∏／6+sinxcos∏／6-cosxsin∏／6)+cosx+a````=2sinxcos∏／6)+cosx+a````=√3sinx+cosx+a`...