Download - Points, Lines, and Planes
Points, Lines, and Planes
GeometryMrs. King
Unit 1, Lesson 2
Definition
Point: a location in space. A point has no size, but is represented by a dot labeled with a capital letter.
A
PQZ
Definition
Space: the set of all points
Definition
Line: a series of points that extends without end in two opposite directions.
PQ
l
Definition
Collinear: points that lie on the same line.
PQ
R
For example, X, Y, and Z and X, W, and Z form triangles and are not collinear.
In the figure below, name three points that are collinear and
three points that are not collinear.
Points Y, Z, and W lie on a line, so they are collinear.
Practice
Definition
Plane: a flat surface that extends in all directions without end.
Shade the plane that contains X, Y, and Z.
Practice
You can name a plane using any three or more points on that plane that are not collinear. Some possible names for the plane shown are:plane RSTplane RSUplane RTUplane STUplane RSTU
Name the plane shown in two different ways.
Practice
Definition
Coplanar: points and lines that are in the same plane.
Practice1. How many planes are represented by the
surfaces of the cube?
2. Name the plane of the front of the cube in two different ways.
3. Name a point that is coplanar with the given points:a. E, F, G
b. B, C, G
Definition
Postulate: an accepted statement of fact.
Four Basic Postulates
1-1: Through any two points there is exactly one line.1-2: If two lines intersect, then they intersect in exactly
one point.1-3: If two planes intersect, then they intersect in a line.1-4: Through any three noncollinear points there is
exactly one plane.
Homework
Points, Lines, and Planes in Student Practice Packet(Page 3, #1-21)