# Fourier series approximation: DC component and fundamental frequency

In the linked image below, what is meant by plotting the DC component and fundamental frequency for a Fourier series approximation?

For dot point 1 does it want me to graph just the DC component basically or for the first harmonic? Basically what is meant by fundamental frequency?

## 1 Answer

Plotting the DC component and only the fundamental frequency means, you should plot the harmonic approximation that uses only $a_0, a_1, b_1$ (i.e. the DC component plus sines and cosines of the first frequency (which is the fundamental frequency). For the second point, you should plot the reconstruction with $a_0, a_1, b_1, a_2, b_2$.

Exactly this problem is treated, including code, at my site.