reserve a,b,c,d,a9,b9,c9,d9,y,x1,u,v for Real,
  s,t,h,z,z1,z2,z3,s1,s2,s3 for Complex;

theorem
  for z be Complex, v be CRoot of 1,z holds v = z
proof
  let z be Complex, v be CRoot of 1,z;
  v|^ 1 = z by COMPTRIG:def 2;
  hence thesis;
end;
