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

Choose freely a point C on the line a (rule WOnline2)

Using the point C and the point M_a, construct a point B (rule W01);

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