Using the point E_c and the point N, construct a line m(H_bH_a) (rule W02);

% DET: points E_c and N are not the same

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

% NDG: points E_c and N are not the same

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

Using the circle k(N,M_a), the line m(H_bH_a), the point N and the point E_c, construct a point M_c (rule W05a);

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

% DET: points E_c and M_c must be different

Choose freely a point A (rule free)

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

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

Using the point E_c and the point H, construct a point C (rule W01);