Using the point H_a and the point M_c, construct a circle k(M_c,A) (rule W06);

% NDG: points H_a and M_c are not the same

Choose freely a point A on the circle k(M_c,A) (rule WOncircle)

Using the point A and the point M_c, construct a point B (rule W01);

Using the point H_a and the point B, construct a line a (rule W02);

% DET: points H_a and B are not the same

Choose freely a point C on the line a (rule WOnline1)