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

% DET: points O and M_a are not the same

Using the point H_c and the point M_a, construct a circle k(M_a,B) (rule W06);

% NDG: points H_c and M_a are not the same

Using the point M_a and the line m_a, construct a line a (rule W10a);

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

% NDG: line a and circle k(M_a,B) intersect

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

% DET: points H_c and B are not the same

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

% NDG: points B and O are not the same

Using the circle k(O,C), the line c, the point O and the point B, construct a point A (rule W05);

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

% DET: points B and A must be different