Chapter 1: Tools of Geometry

Lesson 1: Points, Lines and Planes

Definitions

» Point- represents a location» Line- made up of points and has no thickness or

width, extends infinitely at both ends (cannot be measured)

» Collinear- points on the same line» Plane- flat surface made from points that has no

depth and extends in all directions infinitely» Coplanar- points or lines on the same plane» Space- boundless, 3-D set of all points that contains

lines and planes

Copy the notes into the foldable.

Model Drawn Named By Facts Words/Symbols

Examples

Point

As a dot A capitol

letterA point has neither size nor shape

point P

Line With an arrowhead

at both ends

Two letters representing points on the line- or the script letter

There is exactly 1 line through any two points

line nline AB

line BA

Plane As a shaded,

slanted, 4-sided figure

A capital script letter or by any

three letters of non-

collinear points

There is exactly 1

plane through any three non-collinear points

plane Splane XYZplane XZYplane ZXYplane ZYXplane YXZplane YZX

P

AB

XYZ

S

n

Examples

A. Use the figure to name a line containing point K.

B. Use the figure to name a plane containing point L.

C. Use the figure to name the plane two different ways.

Examples

A. Name the geometric shape modeled by a 10 12 patio.

B. Name the geometric shape modeled by a water glass on a table.

C. Name the geometric shape modeled by a colored dot on a map used to mark the location of a city.

D. Name the geometric shape modeled by the ceiling of your classroom.

Examples

Examples

A. How many planes appear in this figure?

B. Name three points that are collinear.

C. Are points A, B, C, and D coplanar? Explain.