/* -*-ePiX-*- */
#include "epix.h"
#include "cme_style.h"
using namespace ePiX;

double th0(35), th1(70), th2(85);

double f(double th)
{
  return 0.25*(3 + Cos(th));
}

int main()
{
  picture(P(0,0), P(1.5,1), "2.4 x 1.6in");

  begin();
  degrees();

  P O(0,0), pA(polar(f(th1), th1)), pB(polar(f(th2), th2));
  cme_bold();
  line(O, polar(f(th0), th0));
  line(O, pA);
  line(O, pB);

  polarplot(f, 60, 95, 20);

  label(pA, P(2,4), "$A$", t);
  label(pB, P(0,4), "$B$", t);

  label_angle(th0);
  label(polar(0.6*f(th0), th0), P(0,0), "$r$", tl);

  label_angle(th1);
  arc_measure(O, cis(th1), cis(th2), P(2,2), "$d\\theta$", t, 36);

  label_angle(0);
  arc_measure(O, E_1, cis(th0), P(2,2), "$\\theta$", r, 18);

  axis_labels("$O$", "$X$", "");
  line(O, P(xmax(),0));
  caption("Fig.~61.");
  tikz_format();
  end();
}