pcx76233031
幼苗
共回答了10个问题采纳率:90% 举报
2009sin((a+1005)+(a-1005))=sin((a+1005)-(a-1005))
2009sin(a+1005)cos(a-1005)+2009cos(a+1005)sin(a-1005)=sin(a+1005)cos(a-1005)-cos(a+1005)sin(a-1005)
整理,得:2008sin(a+1005)cos(a-1005)=-2010cos(a+1005)sin(a-1005)
即tan(a+1005)/tan(a-1005)=-2010/2008
则所求式=((-2010/2008)+1)/((-2010/2008)-1)
=2009
1年前
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