抛物线上的点到焦点和准线距离相等.设抛物线的焦点为C,原点为O,过P点垂直于准线的直线交准线于N,y轴交准线与L,OL=OC过Q点垂直于准线的直线交准线于M'则有PC = PN,QC=QM'NM/LM = NP/OL = PC/OC = PQ = M'Q = PQ/CQNP/...