1-cosx=1-(1-2sin²x/2)=2sin²x/2所以x→0-原式=lim-√2*sin(x/2)/(2sin(x/2)cos(x/2))=lim-√2/(2cos(x/2))=-√2/2x→0+原式=lim√2*sin(x/2)/(2sin(x/2)cos(x/2))=lim√2/(2cos(x/2))=√2/2不相等所以极...