高数课程妥媒血课件 镭理工大理>> k cos n xdx=0,(n=1,2,…) 2 not k. sin xdx =-(1-cos nT) nT 2K 当n=1,3,5 nC 0当n=2,4,6, k 2k gtx 31.5 ∴f(x)=+(in+sin+ SIn +…) 2 23 252 (-0<x<+∞;x≠0,+2,4,) Http://www.heut.edu.cn   2 0 2 cos 2 1 xdx n k = 0,   =  2 0 2 sin 2 1 xdx n bn k (1− cos )  = n n k , 0 2,4,6, 1,3,5, 2      = = =    n n n k 当 当 ) 2 5 sin 5 1 2 3 sin 3 1 2 (sin 2 2 ( ) +  +  +    = + k k x x x f x (−  x  +; x  0,2,4, ) an = (n = 1,2, )