1.1. Points, Lines, and Planes http://www.ck12.org
Solution:A city is usually labeled with a dot, orpoint, on a globe. A.
Example 2:Which geometric object best models the surface of a movie screen?
A. point
B. line
C. plane
Solution:The surface of a movie screen extends in two dimensions: up and down and left to right. This description
most closely resembles a plane, C.
Beyond the Basics
Now we can usepoint, line, andplaneto define new terms.
Space:The set of all points expanding inthreedimensions.
Think back to the plane. It extended along two different lines: up and down, and side to side. If we add a third
direction, we have something that looks like three-dimensional space, or the real-world.
Collinear:Points that lie on the same line.
Example 3:Which points are collinear?
Solution:P,Q,R,S,andTare collinear because they are all on linew. If a pointUwas above or below linew, it
would benon-collinear.
Coplanar:Points and/or lines within the same plane.
Example 4:
a) List two other ways to label PlaneJ.
b) List one other way to label lineh.
c) AreKandFcollinear? Are they coplanar?
d) AreE,BandFcoplanar?
e) List four points that are non-collinear.
Solution: