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Question 1

Ways to prove two lines are parallel;

Answer 1

1. Show that a pair of corresponding angles are congruent
2. Show that a pair of alternate interior angles are congruent.
3. Show that a pair of same - side interior angles are supplementary.
4. In a plane show that both lines are perpindicular to the third line.
5. Show that both lines are parallel to a third line.

Question 2

What is an axillary line?

Answer 2

An axillary line is a line (or ray or segment) added to a diagram to help in a proof. (Included in the diagram of Theorem 3-11)

Question 3

What is a corollary?

Answer 3

A corollary is a statement that can be proven easily by applying a theorem.