Expert Answer:
:
Try this:
hold on
t = 0:.01:pi;
h1=polar(t,2*t,'--r')
t1=t(1);
[THETA,RHO] = pol2cart(t1,2*t1) %last
t2=t(end);
[THETA1,RHO1] = pol2cart(t2,2*t2) %first
h2=plot(THETA,RHO,'*')
h3=plot(THETA1,RHO1,'r*')
h4=line([THETA THETA1],[RHO RHO1])
legend([h1 h2 h3 h4],'polar line','first value','last value','line from first value to last value')