Given: Line AD Bisects ∠CAB and CA = CD. Prove: Ray CD / / Ray AB. Use a two-column form.

Question

Answer 1

y=z (definition of angle bisector)

x = y (base angles of an isosceles triangle are equal--triangle ACD is isosceles because AC=CD, given)

x = z (transitive property for equality -- or substitution for equality--from the previous two steps)

lines (or rays) CD // AD (when two lines are cut by a transversal such that alternate interior angles are congruent, then those lines are //--x and z are alternate interior angles, definition of alternate interior angles--lines CD and AB are cut by transversal line AD)

You can include the given info as the first two statements.