The vector plot for the problem 1-(a) will be like this. Now, I would recommend trying to do the same thing for the remaining problems for your practice !
[x,y] = meshgrid(linspace(-pi,pi,25),linspace(-pi,pi,25));
Ax = -sin(2*y);
Ay = cos(2*x);
figure
quiver(x,y,Ax,Ay)
