Its length equals the area of the parallelogram defined by vn W.

它的长度等于用vnw定义的平行四边形的面积。

But this is the same thing as taking a dot product between X-Y-Z and a vector that's perpendicular to vn W with a length equal to the area of that parallelogram.

但这和求X-Y-Z和垂直于vnw的向量的点积是一样的这个向量的长度等于平行四边形的面积。