Geometry

1.2 Points, Lines and Planes

1.2 Basic Vocabulary1.2 Basic Vocabulary

PointPoint

has no size , but is has no size , but is represented represented by a dotby a dot .. PP

all geometric figures all geometric figures consist of consist of pointspoints

LineLineextends in 2 directions without extends in 2 directions without

endingending

has length, but no width or thicknesshas length, but no width or thickness(like a point, the picture is symbolic)(like a point, the picture is symbolic)

Line Line dd

PlanePlaneextends in all directions without endingextends in all directions without ending

like a floor or a walllike a floor or a wall

has length and width, but no thicknesshas length and width, but no thickness(like a point and line, the picture is symbolic)(like a point and line, the picture is symbolic)

Plane Plane KK

K

• In Geometry, the terms point, line and plane are

• accepted as intuitive ideas

• not defined

• used in definitions of other terms

Some More DefinitionsSome More Definitions

SpaceSpace the set of all pointsthe set of all points

Collinear pointsCollinear points points all in one linepoints all in one line

Noncollinear pointsNoncollinear points points not in one points not in one lineline

Still MoreStill More

Coplanar pointsCoplanar points points all in one points all in one planeplane

Noncoplanar pointsNoncoplanar points points not all in points not all in one one planeplane

More about linesMore about lines

The intersection of two lines is a The intersection of two lines is a

______________?______________?

PointPoint

More about planesMore about planes

The intersection of The intersection of two planes is a two planes is a

______________?______________?

LineLine

More about planesMore about planes

The intersection of a plane and a line The intersection of a plane and a line not on that plane is a not on that plane is a

______________?______________?

PointPoint

Check for understandingCheck for understanding

Turn to page 7 in your textbookTurn to page 7 in your textbook

Examine the figures on the right side Examine the figures on the right side of the pageof the page

Let’s do Classroom Exercises (CE) Let’s do Classroom Exercises (CE) #1-20 together (you have seen some #1-20 together (you have seen some of these before) Roll the dice!of these before) Roll the dice!

• P. 7 WE # 1-33 odd

P. 10 #40-46 Even

Look at Section 1.3

P. 14 #1-24 (4X) (1,4,8, etc…)

Homework 1B