Using the point H_a and the point N, construct a circle k(N,M_a) (rule W06);

% NDG: points H_a and N are not the same

Choose freely a point E_a on the circle k(N,M_a) (rule WOncircle)

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

% DET: points E_a and H_a are not the same

Using the point E_a and the point N, construct a line m(H_bH_c) (rule W02);

% DET: points E_a and N are not the same

Using the circle k(N,M_a), the line m(H_bH_c), the point N and the point E_a, construct a point M_a (rule W05a);

% NDG: line m(H_bH_c) and circle k(N,M_a) intersect

% DET: points E_a and M_a must be different

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

% DET: points M_a and H_a are not the same

Choose freely a point A on the line h_a (rule WOnline1)

Using the point A and the point E_a, construct a point H (rule W01);

Using the point N and the point H, construct a point O (rule W01);

Using the point A and the point O, construct a circle k(O,C) (rule W06);

% NDG: points A and O are not the same

Using the circle k(O,C) and the line a, construct a point C and a point B (rule W04);

% NDG: line a and circle k(O,C) intersect