1. Geometry Chapter 1 Essentials of Geometry
1.1 Identify Points, Lines, and Planes

2. Undefined Terms have no formal definitions, but there is agreement about what they mean
point
line
plane

3. Point (A) : we just think about it being a dot in space or in a plane that represents a specific location. A
A point is represented by a capital letter

4. Line: A line is represented by two points and a line with
think about it being an infinite number of points connecting in a straight orientation moving in both directions forever
A line is represented by two points and a line with
two arrow heads on each end l A B
line l

5. Plane You name a plane using 3 noncollinear points. Plane ABC
Think of a plane as being a 2 dimensional flat surface that continues forever without bending. 3 noncollinear points if connected create a triangle that lies in a plane.
You name a plane using 3 noncollinear points.
Plane ABC

6. Defined Terms
Line segment
ray

7. part of a line with two endpoints
Line Segment:
part of a line with two endpoints
A line is represented by two points and a line with
two points on each end A B

8. part of a line that has one endpoint
Ray
part of a line that has one endpoint
A ray is represented by one points and a line with
one arrow head A B

9. Opposite Rays
An opposite ray is represented by a shared endpoint points and
a line with one arrow head pointing in the opposite direction C B A

10. Collinear:
When points lie on the same line they are collinear. The word betweeness in geometry implies that all points are collinear
A lies between C and B. A, B, C are collinear. A B C

11. When points lie on the same plane they are coplanar.F H D B C G

12. Parallel Planes
Parallel planes are planes that DO NOT intersect.

13. Perpendicular Planes Perpendicular planes intersect at a right angle.b a c

14. Intersecting Planes
Planes that intersect create a line at all of the intersecting points.