Section 1.2

Points, Lines, and Planes

Undefined Terms

Point

Represents “location”; represented with a dot; no shape or size; 0-dimensional

A

Line

Represents “straightness”; represented with a straight line with two arrowheads; 1-dimensional

A

B

or AB BA$%$%%$%%$%%$%%$%%$%%$%%$%%$%%$%%$%%$%%$% %$%

Plane

Represents “flatness”; represented with a shape that looks like a tabletop; 2-dimensional

P

A B

C

plane P or plane ABC

Other Definitions

Collinear Points

Points on the same line.

Coplanar Points

Points on the same plane.

Line Segment

A portion of a line.

A

B or AB BA

Ray

Consists of an initial point and extends in one direction to infinity.

A

B

not AB BA%%%%%%%%%%%%%%%%%%%%%%%%%%%%

Intersection

The point(s) two geometric figures have in common

Example

Draw 3 non-collinear points.

Example

Sketch the intersection of a plane and a line.

.

Homework

pg 13 # 10-42 even, 49, 56-66 even