Using lines and classifying them is a common task in geometry. It is also a building block for later Geometry lessons, so it's good to have mastered the terminology (goto: Geometry Definitions) before continuing. One you know the words, and know all about the lines, it is much easier to then learn about 2D shapes, and finally 3D shapes. (We won't cover 4D shapes since we can only see in 3 dimensions!)

Let's take a look at a few different scenarios:

[INSERT PICTURE HERE]

1. Line A (red) is a Transveral Line, as it is intersection two other lines (B, in green and C, in blue.)
2. Since lines B and C are parallel, the "corresponding pairs of angles" are equal, or "congruent." (Angles a and e, b and f, etc.)
3. Rays (lines) D and Line E form Vertex V.
4. Rays F and G are perpendicular, forming a right angle (90 angle, denoted with a little box at the angle, as shown.)

After you understand those lines, take a look at this shape:

Which lines are parallel? Perpendicular? The lines forming the top of the cube with the same slope are parallel. Anything not parallel that will collide are perpendicular!

Try a few more using 2D shapes:

1. Which lines are parallel?
2. Which lines are perpendicular?
3. Which lines have corresponding pairs of angles?
4. Name one Vertex and the lines that create it.

Now that we've mastered the basics of lines, we can go to their closely related cousins, Angles. (Or go back to the Math Lessons and select another topic!)