通过延拓为奇函数和恰当的函数两种方式对弦的两端点进行延拓，运用达朗贝尔公式解决了一端固定，另一端作 受迫振动Asin ωt 的有界弦振动的定解问题，通过计算结果表达式直接得出了描述有界弦振动运动的物理量，直观分析出弦振 动的运动过程.同时对该问题进行了拓展，运用行波法解决了一端为齐次的第一类或第二类边界条件另一端为非齐次边界条 件的定解问题.

Through some fit continuation，the one -dimensional finite string vibrating problem with one end fixed and the other end doing forced vibration of Asin ωt is solved by the D'alembert formula. Based on the result expressed in a concise way，some variables to describe wave propagation are obtained and the process of the string vibration is analyzed. Furthermore，the problem of fixing solution with the first or second type boundary condition on one end and inhomogeneous boundary condition on other end is solved by using traveling wave method.