Page 68 - Math Course 1 (Book 2)

Introduction to Geometry

Mo. 9

Lesson 1 undef ned term

In geometry, points, lines, and planes are
considered undef ned terms.

KEY CONCEPTS: Point Line Plane
1. Identify and model points, lines, and planes.
2. Identify collinear and coplanar points and X Y
intersecting lines and planes in space. P A B
3. Interpreting drawings in a f gure. n Z T

point
MO. 9 - L1a A point is simply a location.

Identify and Model Points, line

Lines, and Planes A line is made up of points and has no thickness
or width.

Vocabulary A-Z plane

Let us learn some vocabulary A plane is a f at surface made up of points.

Key Concept Inverse Variation

Point Line Plane

X Y
Model P A B n
Z T

as a shaded, slanted 4–side
Drawn as a dot with an arrow head at each end
f gure

the letters representing two a capital script letter or by the
a capital
Named by points on the line or lowercase letters naming three non-collin-
letter
script letter ear points.
A point has There is exactly one plane
Facts neither shape There is exactly one line through through any three non-collinear
any two points.
nor size points.
plane T, plane XYZ, plane XYZ,
↔ ↔
Words/ Symbol point P line n, line AB or AB, line BA or BA plane YXZ, plane YZX, plane ZXY,
plane ZYX

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