let A, B, C be Point of (TOP-REAL 2); :: thesis: ( A,B,C is_a_triangle implies the_diameter_of_the_circumcircle (A,B,C) = - (the_diameter_of_the_circumcircle (C,B,A)) )
assume A,B,C is_a_triangle ; :: thesis: the_diameter_of_the_circumcircle (A,B,C) = - (the_diameter_of_the_circumcircle (C,B,A))
then the_diameter_of_the_circumcircle (A,B,C) = - (the_diameter_of_the_circumcircle (A,C,B)) by Thm32;
hence the_diameter_of_the_circumcircle (A,B,C) = - (the_diameter_of_the_circumcircle (C,B,A)) by Thm27; :: thesis: verum