I ' m trying to plot this parabolas and hyperbollas and all I am getting is like a triangle and a couple of crossed lines. (with or without scaling=constraint)

with(plots):

polarplot(4/(1+1.1*sin(x))):

polarplot(2/(1-sin(x)),x);

polarplot(2*1.5/(1-1.5*cos(x)),x);

Is it another problem with Maple?

Thanks.