49 terms

# Geometry Ch. 1-Vocab.

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Point
names a location and has no size
Line
a straight path that has no thickness and extends forever
Plane
a flat surface that has no thickness and extends forever
Collinear
points that lie on the same line
Coplanar
points that lie on the same plane
Segment
the part of a line consisting of two points and all the points between them
Endpoint
a point at one end of a segment or the starting point of a ray
Ray
a part of a line that starts at an endpoint and extends forever in one direction
Opposite rays
two rays that have a common endpoint and form a line
Postulate (axiom)
a statement that is accepted as true without a proof.
Coordinate
a point that corresponds to one and only one number on the ruler
Distance
the absolute value of the difference of the coordinates
Congruent Segments
segments that have the same length
Construction
a way of creating a figure that is more precise
Midpoint
the point that bisects, or divides the segment into two congruent segments
Bisects
divides
Segment Bisector
any ray, segment, or line that intersects a segment at its midpoint.
Angle
a figure formed by two rays, or sides, with a common endpoint called a vertex
Vertex
an angle's common endpoint
Interior of an angle
the set off all points between the sides of the angles
Exterior of an Angle
the set of all points outside the angle
Acute Angle
an angle that measures grater than zero degrees and less than ninety degrees
Right angle
an angle that measures ninety degrees
Obtuse Angle
an angle that measures grater than ninety degrees and less than one-hundred-eighty degrees
Straight Angle
an angle formed by two opposite rays and measures one-hundred-eighty degrees
Congruent Angles
angles that have the same measure
Angle Bisector
a ray that divides an angle into two congruent angles
two angles that are in the same plane with a common vertex and a common side, but no common interior points
Linear Pair
a pair of adjacent angles whose non-common sides are opposite rays
Complementary Angles
two angles whose measures have a sum of ninety degrees
Supplementary Angles
two angles whose measures have a sum of one-hundred-eighty degrees
Vertical Angles
two nonadjacent angles formed by two intersecting lines
Perimeter
the sum of the side lengths of the figure
Area
the number of non-overlapping square units of a given size that exactly covers the figure
Base
any side of a triangle
Height
a segment from a vertex that forms a right angle with a line containing the base
Diameter
a segment that passes through the center of the circle and whose endpoints are on the circle
a segment whose endpoints are the center of the circle and a point on the cicle
Circumference
the distance around the circle
Pi
ratio of a circle's circumference to its diameter (3.14)
Coordinate Plane
a plane that is divided into four regions by a horizontal line
Legs
in a right angle triangle, the two sides that form the right angle
Hypotenuse
the side across from the right angle that stretches from one leg to the other
Transformation
a change in the position, size, or shape, of a figure
Preimage
the original figure
Image
a figure after transformation
Reflection
a transformation across a line. Each point and its image are exactly the same distance from the line
Rotation
a transformation about a point. Each point and its image are the same distance from that point
Translation
a transformation in which all the points of a figure move the same distance, in the same direction