PARALLEL LINES - two lines that are always the same distance apart, and will never intersect. Parallel can be abbreviated as ||. An example of parallel lines is on the Italian flag. Lines a and b on the flag are parallel.

PERPENDICULAR LINES - two coplanar lines that intersect and form angles measuring exactly 90 degrees, like the edges of a building. If an angle measures 90 degrees, a square is place where the lines intersect to show that it is a right angle. Perpendicular is often abbreviated as _|_. Line a _|_ b.

SKEW LINES - two lines that do not intersect, and are not parallel. Skew lines are always noncoplanar. An overpass on a highway is an excellent example of skew lines.

COLINEAR - to line on the same line. If can draw a straight line through any number of points, then those points are colinear. The large stone statues on Easter Island are colinear.

NONCOLINEAR - any number of points not lying on the same line.

COPLANAR - on the same plane. a number of object may not be colinear, but if they lie in the same plane, they are coplanar. These bales of hay lie on the same field, so they are like points lying on the same plane.

NONCOPLANAR - any number of points not lying in the same plane.

Get out your paper and get ready to think!

1) Which instance would be an example of colinear points?

(a) corners of a square (b) knots on a rope (c) ornaments on a christmas tree (d) none of the above

2) Which would NOT be an example of coplanar points?

(a) chairs around a TV (b) boats on the ocean (c) airplanes flying in the sky (d) cookies on a cookiesheet

3) Which would be an example of parallel lines?

(a) lanes in a freeway (b) fence posts and wire (c) bow string and an arrow (d) all of the above

4) Which would be an example of a pair of perpendicular lines?

(a) the yellow lines in the center of a road (b) a road going north crossing a road going west (c) lines on a sheet of ruled paper

True or False

5) Skew lines never intersect

6) Skew lines are always parallel

7) Any two points are colinear

8) Any three points are coplanar

9) Noncoplanar and coplanar are the same thing

10) The strings on a guitar are parallel