1. 1.1 The Building Blocks of Geometry
Objectives:
Define basic geometric terms
Investigate postulates about points, lines, & planes.
Warm-Up:
Use only 4 straight lines to cut a pizza into 11 pieces.

2. Vocabulary:
Point:
Can be thought of as a dot that represents a location on a plane or in space. .
Geometric points have no size.

3. Vocabulary: Line: Contains an infinite number of points
Is perfectly straight.
Extends infinitely in two directions.
Has no thickness.
You need at least two points to define a line.

4. Vocabulary:
Plane:
A flat surface that extends infinitely in all directions.
You need at least three points to define a plane.

5. Vocabulary:
Collinear:
Lying on the same line.

6. Vocabulary:
Coplanar:
Lying in the same plane.

7. Vocabulary:
Segment:
A part of a line that begins at one point and ends at another.
A segment of a line has two endpoints.

8. Vocabulary:
Ray:
A part of a line that starts at one point and extends infinitely in one direction.

9. Vocabulary: Endpoint:
A point at the end of a segment or the starting point of a ray.

10. Vocabulary:
Angle:
A figure formed by two rays with a common endpoint.

11. Vocabulary: Vertex of an Angle:
The point in common with the two rays that form an angle.

12. Vocabulary:
Sides of an Angle:
The two rays that form an angle.

13. Vocabulary: Interior and Exterior of an Angle:
If two points, one from each side of an angle, are connected by a segment, the segment passes through the interior of the angle.

14. Vocabulary: Intersect:
When geometric figures have one or more points in common.
The set of points that they have in common is called their “intersection”.

15. Vocabulary: Postulate:
A statement that is excepted to be true without proof (geometry idea).

16. Example 1: Y 2 Name all of the segments in the triangle. X 1 3 Z
Name each of the angles in the triangle in three different ways.
Name the rays that form each side of the angles in the triangle.
Name the plane that contains the triangle.

17. Example 2: m n Classify each statement as true or false.
C, T, & B are all collinear.
RS is the same as RT. S B
C, T, & B name a plane. T
R, T, & C are all collinear. m n
Four rays start at T. R C

18. Example 3: n m S B T Name the intersection of m and n. R C
Name an angle in the figure.
Name the vertex of this angle and the two rays that form the sides of the angle.
Can an angle in the figure be named <T?

19. Example 4: Name the intersection of planes A and B.
Name two coplanar points. x A z y B w

20. Example 5: Name a point on EH. Name the intersection of AB and AE.
Name three collinear points.
Name two coplanar points. B C I A D J F G E H K

21. Example 6:
How many different segments can be named in the following figure? A B C D

22. Example 7:
How many different angles can be named in the following figure? A B C D

23. Homework: Pages 14-15 Numbers 9-37