Which lines are parallel? check all that apply. Lines b, c, d, e, f are cut by transversal a. Clockwise from top left, the angles formed by lines b and a are blank, 89. 5 degrees, blank, blank; by lines c and a are blank, blank, blank, 91. 5 degrees; by lines d and a are blank, blank, 89. 5 degrees, blank; by lines e and a are 88. 5 degrees, blank, blank, blank; by lines f and a are blank, blank, 90. 5 degrees, blank.