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Geometry Vocabulary
Point
an exact location
in space
Line
A straight path that
goes on forever in
both directions
A and B are any 2
points on the line
.B
AB
Ray
A straight path that
goes on forever in
one direction
AB
Starts at A and goes through B
Line
segment
A straight path that
has two endpoints
Plane
A flat surface that goes
on forever in all
directions
AB
plane
ABC
Intersecting
lines
Lines that cross
at one point
AB
CD
Perpendicular Lines that cross at
lines
right angles
AB
CD
Lines (in a plane )
that never cross
AB
CD
Parallel lines
Angles
Angle
is formed when 2
lines or rays intersect
ÐABC
B
ÐB
A
C
Vertex
the point where the 2
lines or rays intersect N
in an angle
Acute
angle
an angle whose
measure is less than
90 degrees
Obtuse
angle
an angle whose
measure is between 90
and 180 degrees
Straight
angle
an angle whose
measure is exactly 180
degrees
Right
angle
an angle whose
measure is exactly
90 degrees
Complementary Two angles whose
measures add up
angles
600
300
to 90 degrees
Supplementary Two angles whose
measures
add
up
angles
to 180 degrees
1300
500
Vertical
angles
Adjacent
angles
Two angles across
from each other
when 2 lines cross
They are always
congruent!
Two angles next
to each other
They share a side
and a vertex