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
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