The definition of parallel lines requires the undefined terms line and plane

Parallel lines never intersect, but they must be in the same plane. The definition does not require the undefined term point, but it does require plane. Because they intersect, perpendicular lines must be coplanar; consequently, plane is not required in the definition.

What did you include in your response? Check all that apply.

Parallel lines do not intersect.

Parallel lines must be coplanar.

Perpendicular lines intersect at one point.

Perpendicular lines intersect  so plane is not required in the definition.

this is poiselle's equation from fluid mechanic in physics. mech eng

your answer is c! hope this : )