例13-3应用导数性质求下列函数的象函数: 1)f(t)=c0s(Of); 2)f(t)=(t) AF: 1)Lcos(at)=LL(sin(at)) (S 0) 2 0S-+ s+0 2由于8(t) 女e(t),LE(D) (以)=D6(切≈n1 s--0=12 2 2 2 ( 0) 1 (sin( ))] 1 :1) [cos( )] [        + − = + = = s s s s t dt d 解 L t L 例13-3 应用导数性质求下列函数的象函数： 2) ( ) ( ). 1) ( ) cos( ); f t t f t t   = = 0 1 1 [ ( )] [ ( )] 1 2) ( ) ( ), [ ( )] = = − = = = s t s dt d L t L s t L t dt d t   由 于  