kill(all)$

van=facebook.com/LearningCalculus$

d2r(%theta):=%theta*%pi/180.0$
r2d(%theta):=%theta*180/%pi$

f(%theta):=-atan((2*  cos((9*%theta)/2)-cos((7*%theta)/2)+2*sin(%theta)*sin((5*%theta)/2)-cos((3*%theta)/2))/
                 (2*(-sin((9*%theta)/2)-sin((7*%theta)/2)+4*cos(%theta)*sin((5*%theta)/2))));

x(%theta):=float(r2d(f(d2r(%theta))));

X(%theta):=float(f(d2r(%theta)));

x(20);

X(20);

x(10);

[X(45),X(1)];