Page 78 - SPARK OF MATH book 4
P. 78
(5-1) Points and Lines.
Description Figure Symbol
A geometric element that
Point P or Point P
has zero dimensions.
A line is a collection of points
Line along a straight path with no AB or BA
A B
end points.
A line segment is a part of a
Line segment line that contacts every point on XY or YX
the line between its end point. X Y
A ray is a part of a line with a
Ray
single end point that goes on PQ
in one direction. P Q
When rays intersect, they form angles.
Acute angle Right Angle Obtuse Angle Straight Angle
Greater than
Less than 90 An exact 90 90 degrees
degrees degrees and less than An exact 180 degrees
180 degrees
There are three types of lines.
Intersecting Perpendicular Parallel
They do not intersect
They have one They intersect when both lines go
common point. each other at right indefinitely in either
angles. direction.
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