Let's use the familiar Cartesian coordinate system with its x and y axes.

让我们使用熟悉的笛卡尔坐标系及其 x 轴和 y 轴。

What about in three dimensions? Well, you add a 3rd axis called the Z axis, which is perpendicular to both the x and y axes.

在三维空间中呢 你添加了第三个轴 叫做Z轴 它与x轴和y轴都垂直。