並前往https://zh.khanacademy.org/math/zh-grade-3/xf2f7ddeeb5caa97a:zh-v2-chang-fang-xing-de-zhou-chang-he-mian-ji/xf2f7ddeeb5caa97a:zh-v2-chang-fang-xing-mian-ji/v/finding-missing-side-when-given-area-math-3rd-grade-khan-academy