Geometry Lesson 1.1A
Coordinate Plane Basics
LG.1.G.2 Represent points, lines, and planes pictorially with
proper identification, as well as basic concepts derived from
these undefined terms, such as segments, rays, and angles
Basic Terms in Geometry:
1. point – a location. It has no size. It is
represented by a small dot and
named a capital letter. A geometric
figure is a set of points.
2. line – an infinite set of points that
extends indefinitely in 2 directions.
3. Collinear Points: points that lie on
the same line
Examples:
l
D
C
B
A
4. Noncollinear points: points that do
not lie on the same line
5. Plane: an infinite set of points that
extends indefinitely in all directions.
6. Space: the set of all points (3D)
7. Coplanar: points and lines that lie in
the same plane
Parts of a line
A
B
C
8. Segment: Two endpoints and all the points
between.
•Ex:
9. Ray: One endpoint and all the points to one side
of that endpoint.
• Ex:
10. Opposite Rays: Two collinear rays with the
same endpoint. They form a line.
• Ex:
Pay close attention to the notation for segment and ray.
Types of Lines and Planes
11. Parallel Lines: Two lines that are in
the same plane and never intersect
12. Parallel Planes: Planes that do not
intersect
13. Skew Lines – Lines that are not
parallel AND not intersecting
Facts in Geometry
14. Theorem: A statement that is proven
to be true
15. Postulate: A statement that is
accepted as true without proof
Some Basic Postulates
a. Through any 2 points is exactly one
line
b. If 2 lines intersect, then they intersect
at exactly one point
c. If 2 planes intersect, they intersect in a
line
d. Through any 3 noncollinear points
there is exactly one plane
Postulates c & d fill in the
blank:
• Plane _________ and Plane_________
intersect in _______.
Hidden Planes
The Coordinate Plane
•
•
•
•
•
•
•
Label the following:
x-axis
y-axis
origin
Quadrants I – IV
The point (3, -2)
The point (1, 5)