Welcome to Day 1 of Geometry!
Section 1.1 - Identify Points, Lines, and Planes
Warm-up: Coach Shapiro is planning strategies for a W-L football
game. Look at the picture on the left below and try to identify which
vocabulary word from the word bank to the right represents the
players, the yard lines, and the field.
Word Bank
Plane
Line
Point
The players are represented by ____________
The yard lines are represented by ____________
The field is represented by ______________
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Key Vocab
Term
Definition
Point
A point has no
dimension. It is
represented by a
dot.
Picture
A line has one
dimension.
Line
Through any two
points, there is
exactly one line.
A plane has two
dimensions.
Plane
Through any
three points not
on the same line,
there is exactly
one plane.
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Collinear points are points that lie on the same line.
Example: Points A and B are collinear since
they both lie on line l.
Coplanar points are points that lie in the same plane.
Example: Points A, B, and C are coplanar since they
all three lie in plane M.
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Term
Definition
Line Segment
Line segment AB
consists of the
endpoints A and B
and all points on
AB that are
between A and B.
Ray
AB consists of the
endpoint A and all
points on AB that
lie on the same
side of A as B.
Intersection
When two or
more geometric
figures have one
or more points in
common.
Picture
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Names/Labels/Symbols: What is the proper notation?
Directions: Draw a picture of the following examples and write the
proper notation where applicable.
2) Ray BA
1) Ray AB
picture
notation
picture
notation
3) Collinear Points A, B, C, D, and E
notation (name the line)
picture
4) Non-Collinear Points A, B, and C
picture
5) Segment GH
picture
notation
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Opposite Rays are rays that share the same endpoint and then
continue in opposite directions. **they are collinear!
Example:
and
are opposite rays in the picture below.
Your turn: Draw a picture of opposite rays
and
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Example 1: Use the picture below to answer the questions to the right.
a. Give two other names for
.
b. Give another name for plane T.
c. Name three points that are collinear.
d. Name four points that are coplanar.
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Example 2: Use the picture below to answer the questions to the right.
a. Give another name for
.
b. (i) Name all rays with endpoint Q.
(ii) Which of these rays are
opposite rays?
Example 3: Use the picture below to answer the questions to the right.
a. Are
and
b. Are
and
the same ray?
the same ray?
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Intersection: When 2 or more geometric figures have one point in
common.
intersection of 2 lines
intersection of 2 planes
a. Sketch a plane and two
intersecting lines that intersect
the plane at separate points.
b. Sketch a plane and two
intersecting lines that do not
intersect the plane.
c. Sketch a plane and two
intersecting lines that lie in
the plane.
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