kill(all);

r(T):=abs((13*sin(T))/(2*cos(T))+(2*cos(T))/sin(T)-1/sin(T)-6/cos(T));

van=facebook.com/LearningCalculus$

r(T);

diff(r(T),T);

solve(%=0,T);

R(T):=second(num(diff(r(T),T)));

newton(t):=float(subst(t,T,T-R(T)/diff(R(T),T)));

newton(0.5131937004114413); float(%*180.0/(%pi))*degrees;