Question

Parallel, intersecting or skew?

Answer 1

Two lines are:

• Parallel if they don't intersect and lie on the same plane
• Intersecting if...well, they intersect at one point
• Skew if they don't intersect and they lie on two different planes

So, we have:

• AB and BC intersect at point B
• AE and BF don't intersect, but both lie on the plane AEFB
• EF and AD don't intersect and don't lie on a common plane
• ABC and ABF intersect on segment AB
• AED and BFC are parallel (they're both perpendicular to plane ABC)