(pictures included, pls )
carlos draws a transversal, t, on two parallel lines ab and cd, as shown below:
he makes the following table to prove that the alternate interior angles are equal:
which is the missing justification?
a) opposite interior angles are congruent when parallel lines are intersecting by a transversal
b) vertical angles formed by two intersecting segments are congruent
c) adjacent angles formed by two interesting segments are supplementary
d) opposite exterior angles are congruent when parallel lines are intersected by a transversal