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21 terms

Geometry Terms

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point
a location in space; it has no size
line
a series of points that extends in opposite directions without end
plane
a flat surface with no thickness. It contains many lines and extends without end in the directions of all its lines
segment
part of a line; it has two endpoints.
ray
part of a line; it has exactly one endpoint. Name its endpoint first
parallel lines
two lines that lie in the same plane and have no points in common
intersecting lines
lines that lie in the same plane and have exactly one point in common
skew lines
lines that lie in different planes; they are not parallel and do not intersect
acute angle
an angle that is less than 90˚
obtuse angle
an angle that is greater than 90˚ and less than 180˚
straight angle
an angle that is equal to 180˚
right angle
an angle that is equal to 90˚
adjacent angles
angles that share a vertex and a side but have no points in their interiors
vertical angles
angles formed by two intersecting lines and are opposite each other. The opposite angles have the same measure
supplementary angles
the sum of the measure of two angles equals 180˚
complementary angles
the sum of the measure of two angles equals 90˚
transversal
a line that intersects two other lines in different points
corresponding angles
angles that lie on the same side of the tranversal and in the same relative position
alternate interior angles
angles between a pair of lines and on the opposite sides of the transversal
vertex
the point of intersection of two sides of an angle or figure
perpendicular lines
lines that intersect to form right angles