Which of the following is true?
a. perpendicular lines never intersect each other.
b. parallel lines always intersect each other
.c. parallel lines are always in the same plane.
d. perpendicular lines are not in the same plane.

C.

Step-by-step explanation:

A - Perpendicular lines always touch each other at least once.

B - Parallel lines never touch.

D- Not always true.

C is true. If they are not in the same plane they are skewed lines.

4 and 5)16.97 or 12√2

6)15.59 or 9√3

7)y = 15.59 or 9√3     x =27

8)17.80