cis and trans are two terms generally used in genetics.
Cis means that it must be on the same strand in order to act. The promoter of gene only acts in cis (a promoter somewhere else will not influence the gene).
Trans means that it need not be on the same DNA strand(of course it can still be, it just isn’t a requirement). The repressor gene acts in trans. It doesn’t really matter where it is located, as long as it makes the repressor protein.
Cheers.
BTW, are you by any chance taking an intro molecular biology college course?