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Lines and Angles
Terra Alta/East Preston School
Geometry Unit
Ray
Ray--part of a line that has one
endpoint and goes on endlessly
in the other direction.
Congruent
Equal in size and shape.
Degrees
70
The unit used to
measure angles.
Line Segment
A part of a line that has
two endpoints.
Line
A series of points that go
endlessly in both directions.
Vertex
The point at which two
rays join together to
form an angle.
Obtuse Angle
An angle that measures more
than 90 degrees.
Acute Angle
An angle that measures
less than 90 degrees.
Right Angle
An angle that measures
90 degrees.
Straight Angle
An angle that measures
180 degrees. (a.k.a. straight
line)
Parallel Lines
Two lines that are equal
distance apart and will
never intersect.
Perpendicular Lines
Two lines that intersect to
form two right angles.
Complimentary Angles
Two angles that
add up to 90
degrees.
Supplementary Angles
Two angles that
add up to 180
degrees.
*****Reminders******
Supplementary
Straight angle
Complimentary
Corner
***Reminders****
means
angle
B
D
Q
R
E
BEF
DER
QRS
DEF
BER
F
S
CIRCLES
Radius: a line
segment whose
endpoints are the
center of a circle
and a point on the
circle.
Diameter
A line segment
that passes
through the center of a
circle and has endpoints
on the circle.
Arc
A
AB
B
Part of a circle
The End