Tools of Geometry
Introduction to Geometry
In geometry a point is usually represented by a dot and labeled with a letter such as A or B. Points are used to name lines, and segments.
Words |
Diagram |
Symbols |
A line extends without end in two opposite directions. |
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 or 
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A ray has one endpoint and extends without end in one direction. |
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A segment has two endpoints. |
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 or 
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Example: From the diagram, identify the line, ray, or segment using words.
Then name it using symbols.
Solution: a. The figure is a ray and is represented by  .
b. The figure is a segment and is represented by  or  .
c. The figure is a line and is represented by  or  .
A plane is a flat surface that extends without end. You can represent a plane by a figure that looks like a floor or a wall. Two different lines in a plane will either be parallel or intersect . Parallel lines never meet. Intersecting lines meet at a point.
Example: a. Which lines are intersecting?
b. Which lines are parallel?
Solution: a.  and  intersect at point B.
 and  intersect at point A.
b.  and  are parallel.
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