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What are alternate interior angles?

Answer 1

Two parallel lines and one transversal intersecting it form #8# different angles.
Two pairs of these angles are called alternate interior.
See picture below.

A pair of angles #a# and #d# are alternate interior.
So is a pair of angles #b# and #c#.

They are called alternate because #a# and #d# (as well as #b# and #c#) lie on opposite sides from transversal #l#.
They are called interior because both #a# and #d# (as well as #b# and #c#) are inside a space between the parallel lines.

Two angles forming an alternate interior pair are always congruent to each other, they have exactly the same measure.

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Answer 2

Ella Armstrong

Alternate interior angles are a pair of angles that lie on opposite sides of a transversal line and on the inside of two lines that are intersected by the transversal. These angles are formed when a transversal intersects two parallel lines. Alternate interior angles are congruent, meaning they have the same measure. In other words, if two parallel lines are intersected by a transversal, then the pairs of alternate interior angles formed are equal in measure.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.