GEOMETRY WITH MR. REEVES
1.1 Points, Lines, and Planes
VOCABULARY
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undefined terms
point
line
plane
collinear points
coplanar points
defined terms
line segment, or segment
endpoints
ray
opposite rays
intersection
LEARNING TARGETS
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1.1 Points, Lines, and Planes
Name points, lines, and
planes
Name segments and
rays
Sketch intersections of
lines and planes
Solve real-life problems
involving lines and planes
Vocabulary: Undefined Terms
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In geometry, the words point, line and plane are
undefined terms. These words do not have formal
definitions, but there are ways to explain their meaning.
POINT
LINE
PLANE
Vocabulary: Point
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A point has no dimension. A dot represents a point.
Vocabulary: Line
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A line has one dimension. It is represented by a line with
two arrowheads, but it extends without end.
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Through any two points, there is exactly one line. You can
use any two points on a line or a single lowercase italic
letter to name it.
Vocabulary: Plane
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A plane has two dimensions. It is represented by a shape
that looks like a floor or wall, but it extends without end.
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Through any three points not on the same line, there is exactly
one plane. You can use three points in the plane that are not
all on the same line or a single uppercase letter to name the
plane.
Vocabulary: Collinear and Coplanar Points
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Collinear points are points that lie on the same line.
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Coplanar points are points that lie in the same plane.
Example 1
Your turn…
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Complete Monitoring Progress #1 in your notebooks:
Vocabulary: Defined Terms
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In geometry, terms that can be described using known
words such as point or line are called defined terms.
LINE SEGMENT
ENDPOINT
RAY
OPPOSITE RAY
Vocabulary: Line Segment
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A line segment, or segment, consists of two
endpoints and all the points between those endpoints.
Vocabulary: Ray
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A ray is a part of a line that has one fixed endpoint and
all the points that extend infinitely along the line from that
endpoint.
Vocabulary: Opposite Rays
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Opposite rays have a common endpoint extending in
opposite directions and form a line.
Example 2
Your turn…
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Complete Monitoring Progress #2-3 in your notebooks:
Vocabulary: Intersection
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Two or more geometric figures intersect when they have
one or more points in common. The intersection of the
figures is the set of points the figures have in common.
EXAMPLES
The intersection of two
different lines is a point.
The intersection of two
different planes is a line.
Example 3
Example 4
Your turn…
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Complete Monitoring Progress #4-7 in your notebooks:
Example 5
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The diagram shows a juice box. Name two different
planes that contain EX.
Your turn…
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Complete Monitoring Progress #8-10 in your notebooks:
Monitoring Progress Answers
VOCABULARY
•
•
•
•
•
•
•
•
•
•
•
•
undefined terms
point
line
plane
collinear points
coplanar points
defined terms
line segment, or segment
endpoints
ray
opposite rays
intersection
LEARNING TARGETS
•
•
•
•
1.1 Points, Lines, and Planes
Name points, lines, and
planes
Name segments and
rays
Sketch intersections of
lines and planes
Solve real-life problems
involving lines and planes