6 a) Prove that if (11) and (12) are two parallel lines with distance d between them, then M12 0 Mi, is a translation by an amount 2d in the direction from (l) to (l2), perpendicular to those lines. Consider only the case when P is between (li) and (12). What other cases we should consider for a complete proof? b) Explain the following statement: the translation from a) depends only on the direction of the paral- lel lines and their distance apart. 6 a) Prove that if (11) and (12) are two parallel lines with distance d between them, then M12 0 Mi, is a translation by an amount 2d in the direction from (l) to (l2), perpendicular to those lines. Consider only the case when P is between (li) and (12). What other cases we should consider for a complete proof? b) Explain the following statement: the translation from a) depends only on the direction of the paral- lel lines and their distance apart