This document provides definitions and examples related to basic geometry concepts: - It defines key undefined terms like point, line, and plane, and provides examples of how to name them. - It introduces defined terms like segment, ray, and opposite rays, giving examples of each. - It discusses the intersection of geometric figures, noting that intersection means figures have one or more points in common. The intersection is the set of common points.

1. DO NOW
1. The distance around a polygon is
called its P_ _ _ _ _ _ _ R, and the
distance around a circle is called its C
_ _ C _ _ _ _ R _ _ _ E .
2. The number of square units covered
by a figure is called it’s A _ _ _ .
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2. SECTION 1.1:
IDENTIFY POINTS, LINES,
AND PLANES
SWBAT: USE THE DEFINED NOTION OF A POINT, LINE, AND DISTANCE ALONG A
LINE TO DEVELOP A DEFINITION FOR LINE SEGMENTS.
GEOMETRY
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3. UNDEFINED TERMS
• Undefined Terms do not have a formal definition in geometry
• Point: Has no dimension. Represented by a dot.
• Line: Has one dimension. Represented by a line with two arrowheads,
but it extends without end.
• Through any two points there is one distinct line. You can use any two
points on a line to name it.
• Plane: Has two dimensions. Represented by a shape that looks like a
floor, but it extends without end.
• Through any three points not on the same line, there is exactly one plane.
You can use any three points on a plane to name it (as long as they are
not on the same line).
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4. EXAMPLES OF UNDEFINED
TERMS
𝑙
Point A
Point B
Point C
Line 𝑙, or
Line AB, or
Line BA
M
Plane M, or
Plane ABC
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5. TYPES OF POINTS
• Collinear Points: Lie on the same line
• Coplanar Points: Lie in the same plane
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6. EXAMPLE 1
1. Give two other names
for 𝑉𝑊 and for plane P.
2. Name three points that
are collinear.
3. Name four points that
are coplanar.
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7. DEFINED TERMS
• Defined Terms can be described using known words such as
point or line.
• Segment (AKA Line Segment): Consist of two endpoints and all
points on the line between those two points.
• Ray: Consists of one endpoint and all the points in one direction
on its line.
• Opposite Rays: Rays beginning at the same endpoint, but
going in opposite directions on the line.
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8. EXAMPLES OF DEFINED TERMS
Use line 𝐴𝐵 as beginning
term.
Segment AB, or 𝐴𝐵, or
𝐵𝐴
Endpoint
s
Ray AB or 𝐴𝐵
Opposite Rays:
𝐸𝐺 𝐸𝐷
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9. EXAMPLE 2
1. Give another name for
𝐴𝐵.
2. Name all rays with
endpoint D. Which of
these rays are opposite
rays?
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10. INTERSECTIONS
• Two or more geometric figures intersect if they have one or
more points in common.
• The intersection of a figure is the set of points they have in
common.
q
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11. ASSIGNMENT
1. Sketch a plane and a line that is in the plane.
2. Sketch a plane and a line that does not intersect the
plane.
3. Sketch a plane and a line that intersects the plane at
a point.
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12. EXAMPLE 4
1. Sketch two different lines that intersect a plane at
the same point.
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13. HOMEWORK
•Textbook pages 5-7
•#’s 3-6, 8, 9, 12, 15, 17, 18, 23, 26
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