Fourier Transform, plotting for proof

Hello everyone,

I'm having a lot of confusion about Fourier Transform on matlab...I am given two functions, x1 = cos(5t) & x2 = sin(3t) and I am told to solve x(t)= x1*x2 (Which i do not know how to do it yet...)

I am told that, I need to plot the new coefficients of the Fourier Transform and compare it to the plot x(t) and show that both are the same. How can you prove this?

I tried plotting it by using fft but the values seem somehow similar, although the points are different.

Any help is greatly appreciated it Thanks.

[Rick Rosson]

Please show what you have tried so far.