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Basic Terms: Lines
- A line is like a "straight line" that one would draw on paper
using a ruler. However, in geometry a line extends on forever in
both directions. A
line must pass through at least 2 different points. The line is
named using the names of the points it runs through. For example, a
line that runs through points A and B will be called "line AB,"
and will be represented by the letters AB with a double headed arrow over
them. Points -
A point is like a "dot" that one would draw on a piece of
paper. A point has no length or width. It is the
representation of an exact location. A point is named using a number
or letter. Intersection
- Intersection occurs when lines, line segments, rays or figures share a
common point. The shared point is referred to as the point of
intersection. Line
Segments - Unlike a line, a line segment does not extend
forever. It has two distinct endpoints. A line segment with
endpoints A and B is notated by writing the letters AB with a line,
without arrow heads, over them. Rays
- A ray is a line that begins at a certain point and extends forever in
one direction. In other words, a ray has one distinct end
point. This end point is where the ray begins. To notate a ray
that begins with endpoint A and passes through point B, extending on
forever, one would write AB with a singleheaded arrow over
it. Endpoints
- An endpoint is a type of point that is used to define the beginning
and/or end of a line segment or ray. Parallel
Lines - Parallel lines are two lines in the same plane that never
intersect.
Transversal - A line that cuts
across a pair or set of lines, or across the plane of a
figure.
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