Answer :
a) AB is parallel CD from graphic;
b) m AB = (3-1)/(2-0) => m AB = 1; m CD = (7-5)/(6-4) => m CD = 1 => m AB = m CD => AB is parallel CD;
b) m AB = (3-1)/(2-0) => m AB = 1; m CD = (7-5)/(6-4) => m CD = 1 => m AB = m CD => AB is parallel CD;