Why is the denominator and numerator of Fourier coefficient (in Fourier series(exponential) expansion) have a conjugate of the exponential set?

97 Views Asked by At

In the exponential Fourier series, the coefficient Fn takes both the conjugate and original of the exponential set in its denominator and numerator. This doesn't make any sense when seen from the principle of error of least squares which is supposed to derive the Fourier coefficient. Where am I going wrong?Please explain.