beginfig(1); numeric u ; u=4.5cm; for i=1 upto 11: draw (cosd(180+i*15)*u,sind(180+i*15)*u)-- (cosd(i*15)*u,sind(i*15)*u) dashed evenly; endfor; drawarrow (-1.2*u,0)--(1.2*u,0) withpen pencircle scaled 1.5 pt withcolor red; drawarrow (0,-1.2*u)--(0,1.2*u) withpen pencircle scaled 1.5 pt withcolor red; draw fullcircle scaled 9cm withcolor red withcolor blue; label.ulft(btex $\pi$ etex scaled 1, (-u,0)); label.urt(btex $\pi \over 4$ etex scaled 1, ((sqrt(2)/2)*u,(sqrt(2)/2)*u)); label.urt(btex $\pi \over 6$ etex scaled 1, ((sqrt(3)/2)*u,(1/2)*u)); label.urt(btex $\pi \over 3$ etex scaled 1, ((1/2)*u,(sqrt(3)/2)*u)); dotlabel.top(btex $1 \over 2$ etex scaled 0.75, ((1/2)*u,0)); dotlabel.rt(btex $1 \over 2$ etex scaled 0.75, (0,(1/2)*u)); dotlabel.lft(btex $\sqrt(2) \over 2$ etex scaled 0.75, (0*u,(sqrt(2)/2)*u)); dotlabel.bot(btex $\sqrt(2) \over 2$ etex scaled 0.75, ((sqrt(2)/2)*u,0)); dotlabel.rt(btex $\sqrt(3) \over 2$ etex scaled 0.75, (0*u,(sqrt(3)/2)*u)); dotlabel.top(btex $\sqrt(3) \over 2$ etex scaled 0.75, ((sqrt(3)/2)*u,0)); label.urt(btex $\pi \over 2$ etex scaled 1, (0,u)); endfig; end