How do I convolve delta functions in Fourier transform calculations?

[jackdaniel]

Hi everyone, I need help finding the Fourier transform of Cos(10t)sin(t)

i know that i need to find the transform of cos and sin and then convolve them, but i m not sure how to convolve delta function. I would really appreciate any helps.

 

[uart]

No it's better to do it by simplifying the trig expression first using the "half sum difference" identities.

That is, cos(10t)sin(t) = 1/2 ( sin(11t) - sin(9t) )

 

[jackdaniel]

thanks, the way you described made it a lot easier. By using your method I realized that convolving delta functions is simply adding the frequency shifts.

thanks