The three axes determine three planes , the - , - and - plane . which divide space into eight octants . to each pointin space corresponds an ordered triple of numbers . its cartesian coordinates , which measure its directed distances from the three planes 三個坐標決定三個坐標面,面,面,面,這些坐標面將空間分成八個卦限,空間中點每個點都對應一個有序三元組和分別表示點到三個坐標面的有向距離