注意到: ,a>0 +oo sin ax 2 0 ,a<0 (1)若a>|λ|,则a->0且a+~>0,于是有: sIn ax FLf(x)= Fl 22 2)若a=||,则: 0.>0 2a.>0 a+1= 2a,1<0 0.<00.8 1 0.6 0.4 0.2 0 x t 0 0.5 1 1.5 2 −1 −0.5 0 0.5 1 n 13 注意到: 0 , 0 sin 2 , 0 2 a ax dx x a + = − (1) 若a>|λ|,则a-λ>0且a+λ>0,于是有: sin [ ( )] [ ] 2 2 ax F f x F x = = + = (2) 若a=|λ|,则: 0, 0 2 , 0 a a − = 2 , 0 0, 0 a a + =