Using the point B and the point G, construct a point M_b (rule W01);

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

% DET: points B and H_a are not the same

Using the point H_a and the point M_b, construct a circle k(M_b,C) (rule W06);

% NDG: points H_a and M_b are not the same

Using the circle k(M_b,C), the line a, the point M_b and the point H_a, construct a point C (rule W05);

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

% DET: points H_a and C must be different

Using the point G and the point C, construct a point M_c (rule W01);

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