Graph line not showing

So I have an equation and some variables to substitute in for, but I cannot get my graph to have a line. I know others have asked similar questions but I am stuck.

X = 20;

P = 20;

r = 20;

theta = 30;

y = ((X*P)./(2*pi*r.^2))*cos(theta).^(X-2);

plot(y)

Answer 1

[Asad (Mehrzad) Khoddam]

Several issues in your code:

1- it has only one point (use plot(x, y) )

2- The angle should be in radians not degrees. For angles in degrees you can use 'cosd' instead of 'cos'