⑩天掌 Teaching Plan on Advanced Mathematics o 傅里叶级数 +∑(anC0sHx+ b sinn) H=1 问题: f(x)条件?0+∑ (a, cos nx+ b sin nx) tianjin polytechnic dmivendityTianjin Polytechnic University Teaching Plan on Advanced Mathematics 傅里叶级数 +  +  =1 0 ( cos sin ) 2 n an nx bn nx a 问题: +  +  =1 0 ( cos sin ) 2 ( ) ? n an nx bn nx a f x 条件