Points, Lines and Planes

1
Section 1-2

• Points, Lines and Planes

2
A Point
A

• A point represents a position in space.
• It is named using capital printed letters.

3
A Line
l
A
B

• Two points determine a line.
• A line is an infinite set of points that extends
  in two directions without ending.
• It is named using a single lower case cursive
  letter or by two points on the line,

AB
4
Noncollinear
Collinear

• Points that are on the same line.

• Points that ARE NOT on the same line.

5
A Plane
A
B
C
M

• At least three noncollinear points determine a
  plane.
• A plane is an infinite amount of points that
  creates a flat surface that extends without
  ending.
• Has no thickness
• Usually pictured as a parallelogram, although it
  has NO edges
• It is named using a capital cursive letter

6
Noncoplanar
Coplanar

• Points in the same plane

• Points NOT in the same plane

7
Example 1

• Name collinear points
• Name coplanar points
• c.Name 3 points that are not coplanar

A, B, C
A, B, D, F, C
G
C, G, F
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Line Segment
A
B

• Part of a line consisting of two endpoints and
  all points in between
• It is named using the two endpoints, AB

9
Ray

• Part of a line with an initial point and all
  points going in one direction
• It is named using the endpoint first followed by
  another letter on the ray, AB
• Why cant we name the ray above as BA?

10
Opposite Rays

• Have the same initial point going in opposite
  directions (180)
• CA and CB

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Intersection

• Two or more geometric figures intersect if they
  have one or more points in common.
• Line l and k intersect at point p