Undefined terms in Geometry
Geometry III
1st Grading Period
I. Undefined Terms
1. Point- though we represent a point with a dot, the point has no length, width, or thickness. A point is usually named with a capital letter. In the coordinate plane, a point is named by an ordered pair, (point A) .
A
2. LINE –In geometry, a line has no thickness but its length extends in one dimension and goes on forever in both directions. A line is depicted to be a straight line with two arrowheads indicating that the line extends without end in two directions. A line is named by a single lowercase written letter or by two points on the line with an arrow drawn above them A P B AB • • •
Subsets of a Line
A. Line segment-A line segment is the portion of a line that includes two particular points and all points that lie between them, while a ray is the portion of a line that includes a particular point, called the end point, and all points extending infinitely to one side of the end point
AB and PB
Between
-if AP+BP=AB B. Ray-A ray is a part of a line that begins at a particular point (called the Endpoint) and extends endlessly in one direction. A ray is also called half-line.
3. Plane- plane has no thickness but extends indefinitely in all directions. Planes are usually represented by a shape that looks like a tabletop or wall. Even though the diagram of a plane has edges, you must remember that the plane has no boundaries. A plane is named by a single letter (plane m) or by three non-collinear points (plane ABC).
II. Definition
Coplanar- A set of points, lines, line segments, rays or any other geometrical shapes that lie on the same plane are said to be Coplanar.
Collinear-Passing through or lying on the same straight line
POSTULATE or Axiom -accept w/o a proof
Postulate 1
Two point determine a line A B
Postulate 2
3 collinear
1st Grading Period
I. Undefined Terms
1. Point- though we represent a point with a dot, the point has no length, width, or thickness. A point is usually named with a capital letter. In the coordinate plane, a point is named by an ordered pair, (point A) .
A
2. LINE –In geometry, a line has no thickness but its length extends in one dimension and goes on forever in both directions. A line is depicted to be a straight line with two arrowheads indicating that the line extends without end in two directions. A line is named by a single lowercase written letter or by two points on the line with an arrow drawn above them A P B AB • • •
Subsets of a Line
A. Line segment-A line segment is the portion of a line that includes two particular points and all points that lie between them, while a ray is the portion of a line that includes a particular point, called the end point, and all points extending infinitely to one side of the end point
AB and PB
Between
-if AP+BP=AB B. Ray-A ray is a part of a line that begins at a particular point (called the Endpoint) and extends endlessly in one direction. A ray is also called half-line.
3. Plane- plane has no thickness but extends indefinitely in all directions. Planes are usually represented by a shape that looks like a tabletop or wall. Even though the diagram of a plane has edges, you must remember that the plane has no boundaries. A plane is named by a single letter (plane m) or by three non-collinear points (plane ABC).
II. Definition
Coplanar- A set of points, lines, line segments, rays or any other geometrical shapes that lie on the same plane are said to be Coplanar.
Collinear-Passing through or lying on the same straight line
POSTULATE or Axiom -accept w/o a proof
Postulate 1
Two point determine a line A B
Postulate 2
3 collinear