😃5.3 點積

10.6 向量的內積 | 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/10.6-xiang-liang-de-nei-ji

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https://www.geogebra.org/m/XShfg9r8

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