Determine whether line AB is parallel or perpendicular to CD in each case.
(a) A(0, 0), B(0, 1), C(0, 0), D(1, 0).
(b) A(0, 1), B(2, 3), C(4, 5), D(6, 7).
Answer (1)
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;
