Im having problem solving this question

x(t) = cos(200*pi*t+pi/4), (Dt=0.0001s, t=0~20 sec, axis([0 0.1 -1.1 1.1]));

1.plot x(t) in time domain and its Fourier Transform (magnitude and phase axis([-110 110 oo oo]).

2.if fs= 500 Hz, plot x(t) in time domain and its Fourier Transform (magnitude and phase axis([-110 110 oo oo]).

3.if fs= 150 Hz, plot x(t) in time domain and its Fourier Transform (magnitude and phase axis([-110 110 oo oo]).

4.if fs= 80 Hz, plot x(t) in time domain and its Fourier Transform (magnitude and phase axis([-110 110 oo oo]).

[Walter Roberson]

https://www.mathworks.com/matlabcentral/answers/6200-tutorial-how-to-ask-a-question-on-answers-and-get-a-fast-answer