Try Maxima plugin
[MATH=eng]Maxima(assume(ω>0))=ω>0[/MATH]
[MATH=eng]Maxima(laplace(sin(ω*t),t,s))=ω/{s^2+ω^2}[/MATH]
[MATH=eng]Maxima(ilt(ω/{s^2+ω^2},s,t))=sin(ω*t)[/MATH]
Regards,
Radovan
When Sisyphus climbed to the top of a hill, they said: "Wrong boulder!"