⑩天掌 Teaching Plan on Advanced Mathematics o 其中系数an,b为 nTtr f(x)cos",x,(n=0,1,2,…) nth f(x)sin",dx,(n=1,2,…) (1)如果f(x)为奇函数,则有 f(x)=∑bsin nTcr 其中系数b为b2 T x sin dx (n=1,2,…) tianjin polytechnic dmivendityTianjin Polytechnic University Teaching Plan on Advanced Mathematics 其中系数an , bn为 ( )cos , ( 0,1,2, ) 1 =   = − dx n l n x f x l a l l n ( )sin , ( 1,2, ) 1 =   = − dx n l n x f x l b l l n (1)如果f (x)为奇函数, 则有 ( ) sin , 1   =  = n n l n x f x b ( )sin , 2 0 dx l n x f x l b b l n n   其中系数 为 = (n = 1,2, )