reserve p1,p2,p3,p4,p5,p6,p,pc for Point of TOP-REAL 2;
reserve a,b,c,r,s for Real;
reserve c1,c2,c3 for Element of COMPLEX;

theorem
  angle(c1,c2) + angle(c2,c3) = angle(c1,c3) or angle(c1,c2) + angle(c2,
  c3) = angle(c1,c3) + 2*PI by Lm14;
