# Can I find the Fourier series expression from given terms?

I found the fundamental frequency, and all the harmonic components (an, bn), but is it possible to find the fundamental expression of an ,bn or cn? -The last part of the question-

• It's not clear what you're asking, you must have used an expression to get $a_n$ and $b_n$. Also, what's $c_n$? – Chu Feb 13 '16 at 8:59
• Cn is the complex form of the series...but the question wants the revers steps, it gives me an and bn; and i must find the expression – Mohammad Asmar Feb 13 '16 at 9:00
• Do you mean writing the harmonics in the form $a_n sin \:(n\:\omega t)$? – Chu Feb 13 '16 at 9:03
• Do you mean you want to find a mathematical expression for the signal, like f(t) = ...? – Bart Feb 13 '16 at 9:08
• It would help if you added to your question the formula in which an, bn and cn fit in. It is unclear what these are referring to. – jippie Feb 13 '16 at 9:26

$cos(n\omega t)= \dfrac{e^{jn\omega t}+e^{-jn\omega t}}{2}$
$sin(n\omega t)= \dfrac{e^{jn\omega t}-e^{-jn\omega t}}{j2}$
with $n=1;\:n=3;\:n=11$, and $\omega=\frac{4\pi}{3}$