😃5.4 叉積

10.7 空間向量的外積 | 基礎數學xu-shi-min.gitbook.io

https://xu-shi-min.gitbook.io/ji-chu-shu-xue-yi-si-xian-shang-zi-yuan/di-10-zhang-xiang-liang/10.7-kong-jian-xiang-liang-de-wai-ji

https://www.geogebra.org/m/psMTGDgc

https://www.geogebra.org/m/ujjgekeq