Question

which of the angles formed by parallel lines intersected by a transversal are congruent(there are 6 different angle pairs that exist when lines intersect)

Answer 1

Alternate angles or vertical angles: are those that are on a different side of the secant.

For example ∠1 and ∠2 are vertical angles.

Collateral angles: are those that are on the same side of the secant.

For example ∠1 and ∠2 are collateral angles.

Alternate angles:

Alternate interior angles: are those that are in the interior zone of the parallel lines.

Alternate exterior angles: are those that are in the external zone of the parallel lines.

For example ∠1 and ∠2 are alternate interior angles and ∠3 and ∠4 are alternate exterior angles.

Corresponding angles: are those that on the same side of the secant, one is external and the other internal.

For example ∠1 and ∠2 and ∠3 and ∠4 are corresponding angles.