reserve SAS for Semi_Affine_Space;
reserve a,a9,a1,a2,a3,a4,b,b9,c,c9,d,d9,d1,d2,o,p,p1,p2,q,r,r1,r2,s,x, y,t,z
  for Element of SAS;

theorem
  not o,p,c are_collinear & o,p,b are_collinear & qtrap o,p implies ex d
  st trap p,b,c,d,o
proof
  assume that
A1: ( not o,p,c are_collinear)& o,p,b are_collinear and
A2: qtrap o,p;
  consider d such that
A3: o,p,b are_collinear implies o,c,d are_collinear & p,c // b,d by A2;
  take d;
  thus thesis by A1,A3;
end;
