1. Aim: What are some basic terms of Geometry?
HW # 2: p19-21/1-16 odd, 68, 72
Do Now: Copy the diagram of the 4 points A, B, C and D. Draw as many different lines as you can to
connect pairs of points.
1) How many lines can you draw to connect pairs of points in the figure?
2) Based on your observation, make a conjecture about the minimum number of points necessary to form a line.

2. In geometry, definitions are formed using known words or terms to describe a new word. There are 3 words in geometry that are not formally defined. These 3 undefined terms are point, line and plane.
Characteristics of a point:
no dimension (no size)
represented by a dot
named using a capital letter
a location named using an ordered pair on the coordinate plane
Characteristics of a line:
no thickness
its length extends in one dimension and goes on forever in both directions
named using a lowercase letter or by any two points on the line
Characteristics of a plane:
a flat surface
contains an infinite number of lines
extends without end in all directions
named by either a single capital letter or by at least 3 of its non-collinear points. A B C D A B C l P A B C A B C D

3. Collinear points are points that lie on the same line.
Points A, B and C are collinear. A B C

4. Copy the figure Are points A, B and D collinear?
If so, name the line on which they lie.
Are points G, F and D collinear?
If so, name the line on wich they lie.

5. l m
Name line l in three other ways.
Name GF in three other ways.

6. Draw the figure. Each surface of the cube represents a plane.
Name the plane represented by the front of the cube.
List 3 different names for the plane represented by the top of the cube. A B D C G H E F

7. 6. Are points A,B and C collinear?
7. Are points A,D and E collinear?

8. TRUE or FALSE? 1. A point has size. 2. A line is a series of points.
3. A line extends in two opposite direction with end.
4. A plane has a boundary.
5. Point, line and plane are defined terms in geometry.