Geometry 1.1 - Undefined Terms
What does geometry mean? It means "to measure the Earth" or "Earth measure." However, we can simply look at geometry in a more simple way as the study of figures or shapes.
Some basic terms in geometry can be described and others cannot.
Undefined Terms:
Point: A point shows location and has no size or dimension. A point is represented by a dot and is usually named with a letter of choice. In the graphic below, the points are labelled by a nearby letter.
Line: A line is a set of points extends in two opposite directions without end. A line is one-dimensional and has no width. It is identified by naming two points on the line or by writing a lowercase letter of choice after the line.
The notation, for example, AB (written with a line symbol <---> over the letters), is read as "line AB" and refers to the line that has points A and B.
Plane: A plane is a flat surface that has no thickness and extends without ending in ALL directions. It is a two-dimensional object. A plane is represented by a parallelogram and may be named by writing an uppercase letter of choice in one of its corners. I will go into detail about what a parallelogram is in future lessons. For now, think of a parallelogram as a "window pane."For simplicity, you might want to think of a plane as an infinitely large sheet of paper.
The diagram below shows three points, a line, and a plane.
End of lesson one. Look for my next lesson titled Defined Terms.
By Mr. Feliz
(c) 2007
