DO NOW

• Take a ruler from the bookshelf. • Have your syllabus contract out and ready to turn

in. • Take out your notebook for this class.• In your notebook, describe the two types of

symmetry and draw an example of each.

BUILDING BLOCKS OF GEOMETRY

TODAY’S OBJECTIVES

• Learn the terminology and notation of points, segments, lines, rays, planes, angles, and collinear and coplanar points.• Learn the idea of congruence of line segments• Learn how to mark congruence of segments on

diagrams• Begin keeping a notebook of definitions• Develop Problem Solving Skills

UNDEFINED TERMS

• Point• Line • Plane• The three most basic building blocks of geometry.

POINT

• Has no size.• Only has location• Represented with a dot• Named by a capital letter

LINE

• Straight continuous arrangement of infinitely many points.• Has infinite length but no thickness• Extends forever in two directions• Named by the letter names of any two points on

the line and the line symbol.

PLANE

• Has length and width, but no thickness.• Flat surface that extends infinitely along its

length and width.• Represented with a 4-sided figure, like paper.• Named with a script capital letter.• P

ANCIENT “DEFINITIONS”

• “A point is that which has no part. A line is breadthless length.” –Greeks• “The line is divided into parts, and that part which

has no remaining part is a point.” –Chinese

IMPOSSIBLE TO DEFINE

• We would have to use the terms point, line, and plane to define them. • So we accept them as undefined and use them to

define everything else in Geometry.

COLLINEAR

• On the same line.

COPLANAR

• On the same plane

RAY

• Part of a line• Has an endpoint but extends forever in one

direction.

ANGLE

• Made up of two rays who share an endpoint.

LINE SEGMENT

• Consists of two endpoints of the segment and all the points between them that are collinear with the two points.

CONGRUENT

• Two segments are congruent if they have equal measures or lengths.

PRACTICE

PRACTICE

PRACTICE

TODAY’S OBJECTIVES

• Learn the terminology and notation of points, segments, lines, rays, planes, angles, and collinear and coplanar points.• Learn the idea of congruence of line segments• Learn how to mark congruence of segments on

diagrams• Begin keeping a notebook of definitions• Develop Problem Solving Skills

EXIT SLIP

1. Draw and mark a figure in which M is the midpoint of ST, SP=PT and T is the midpoint of PQ.

2. Explain your reasoning. 3. Draw an example of collinear points. 4. Define coplanar.