並前往https://math.ymhs.tyc.edu.tw/masterchen/chenjt99/ScrClass/1092/%E9%AB%98%E4%B8%80%E7%BF%92%E9%A1%8C/109%E4%B8%8B%E9%AB%98%E4%B8%80%E7%BF%92%E9%A1%8C(ch4.2).pdf
