The application of a $10-\mathrm{mV}, 100-\mathrm{kHz}$ square wave to an amplifier resulted in the output waveform of Fig. 90 .
a. Write the Fourier series expansion for the square wave through the ninth harmonic.
b. Determine the bandwidth of the amplifier to the accuracy available by the waveform of Fig. 90 .
c. Calculate the low-cutoff frequency