A: F,(s)=L[sin ot. 8(0)=L/eyot-e-jou 8(t js-jo 2jS+j F2(S)=LL2() LI KE( a(t) KK Ka sS+a s(s+a 闪四 西南交通大学西南交通大学 2 2 1 2 1 1 2 1 w w w w + = + - - = j s j j s j s ( ) L[ ( )] 2 2 F s = f t L[ K (t)] L[ Ke (t)] t e e - a = - ( a ) a a + = + = - s s K s K s K 解： ú û ù ê ë é × e - = w × e = w - w ( ) 2 ( ) [sin ( )] 1 t j e e F s t t j t j t L L