√3/3=AM/(AM-40)AM-40=AM/(√3/3)AM-40=√3AM√3AM-AM=-40(√3-1)AM=40AM=40/(√3-1)顷好链AM=40(√3+1)/【(√雀孙3+1)(√3-1)】AM=40(√3+1)/(3-1)AM=20(√3+1)袜渗
用十字相乘法进行计算