8.23 A triangle wave with period 1/20 s has the truncated Fourier series expansion 1 cos(220) + cos(2(3)20) + cos(2 (5)20). 25 Write a MATLAB or MathScript program that adds noise randn (1,N) to this triangle wave. Use a sampling rate of 44,100 samples per second and signal length N = 11025. Use thresholding and the DFT to eliminate the noise in the signal. Plot the noisy and filtered waveforms for 0 < t < 0.25 s.