plotting for cosine wave

Hey guys.

I need to plot this curve. The teta should be 90 and I neesd to plot it for teta 0~360. Can you please help me?

N=45;

teta=90;

Na1=2*N*cos(teta);

Nb1=2*N*cos(teta-30);

Nc1=2*N*cos(teta-60);

Na2=2*N*cos(teta-90);

Nb2=2*N*cos(teta-120);

Nc2=2*N*cos(teta-150);

plot(teta,Na1+Nb1+Nc1+Na2+Nb2+Nc2)

Answer 1

[Rafael Hernandez-Walls]

I change some lines....

N=45;
theta=0:360; % range of values of theta
Na1=2*N*cosd(theta);  % cosd for cos  when you use degree
Nb1=2*N*cosd(theta-30);
Nc1=2*N*cosd(theta-60);
Na2=2*N*cosd(theta-90);
Nb2=2*N*cosd(theta-120);
Nc2=2*N*cosd(theta-150);
plot(teta,Na1+Nb1+Nc1+Na2+Nb2+Nc2)

[Ali Roshanzamir]

Thank you very much. Actually I need a constant theta=90 and I need to plot it for 360 degree. I don't want the variable theta. If possible please consider this as well.

thanks