⑩天掌 Teaching Plan on Advanced Mathematics o a. cos2md=an冗 f∫(x) cos nro(n=1,2,3,…) (3)求bn ∫(x) sinned sinned +Ela[ cos kx sin ndxb sin kr sin/xx l =b,T, f(x)simn(n=1,2,3,…) T tianjin polytechnic dmivendityTianjin Polytechnic University Teaching Plan on Advanced Mathematics =   − an nxdx 2 cos = , an   =  − a f x nxdx n ( )cos 1 (n = 1,2,3, ) (3) . 求bn   =  − bn f (x)sinnxdx 1 (n = 1,2,3, ) − − =     nxdx a f x nxdx sin 2 ( )sin 0 [ cos sin sin sin ] 1     −  −  = + a kx nxdx + bk kx nxdx k k = , bn