Question

If two lines are parallel, which statement must be true?

A. Their slopes are reciprocals.
B. Their slopes are opposites.
C. Their slopes are equal.
D. Their slopes are negative reciprocals.

Answer 1

C. Their slopes are equal.

Explanation:

Given : If two lines are parallel.

To find : which statement must be true.

Solution : We have given that If two lines are parallel.

We know that two parallel line have same slope

By rise over run :

Therefore, C. Their slopes are equal.

Answer 2

I believe the correct answer from the choices listed above is option C. If two lines are parallel, their slopes are equal. Having equal slopes mean that the rise and run of the points of the lines are the same. Parallel lines do not intersect even when extended infinitely.