A triangle wave with period T0 = 1/20 has the truncated Fourier expansion (recall Week 5 for CT Fourier series) x(t) = cos(2π · 20t) + 1 9 cos(3 · 2π · 20t) + 1 25 cos(5 · 2π · 20t) (i) Write a Matlab program that adds noise randn(1, N) to this triangle wave. (ii) Use a sampling rate of 44100 samples per second and signal length N = 11025 to get a discretetime signal x[n]. (iii) Use thresholding and DFT to eliminate the noise in the signal. (iv) Plot the noisy and filtered wave forms for 0 ≤ t ≤ 0.25.