# Math Help - Fourier coefficients of real functions are real

1. ## Fourier coefficients of real functions are real

Hello. I am asked to show that fourier coefficients of a function that just takes real values $a_n,b_n$ are real.
It seems pretty obvious but I can't find a proof,
Any help?

Thank you very much!!

2. ## Re: Fourier coefficients of real functions are real

it's not true.

For example the 2 coefficients of $f(t)=\sin(\omega_c t)$ are

$a_1 = a_{-1} = \dfrac 1 {2 \imath}$