51 terms

# Geometry Chapter 1 Terms

#### Terms in this set (...)

acute angle
A angle that measures greater than 0 degrees and is less than 90 degrees
Two angles in the same plane with a common vertex and a common side, but not common interior points
angle
A figure formed by two rays with a common endpoint
angle bisector
A ray that divides an angle into two congruent angles
area
The number of non-overlapping unit squares of a given size that will exactly cover the interior of a plane figure
base
Any side of a triangle
bisect
To divide into two congruent parts
circumference
The distance around a circle
collinear
Points that lie on the same line
complementary angles
Two angles whose measures have a sum of 90 degrees
congruent angles
Angles that have the same measure
congruent segments
Two segments that have the same length
coordinate
A number used to identify the location of a point
coordinate plane
A plane that is divided into four regions by a horizontal line called the x-axis and a vertical line called the y-axis
coplanar
Points that lie in the same plane
degree
A unit of angle measure
diameter
A segments that have endpoints on the circle and passes through the center of the circle; also the length of the segment
distance
The absolute value of the difference of the coordinates of the points
endpoint
A point at an end of a segment or the starting point of a ray
exterior of an angle
The set of points outside an angle
height
A segment from any vertex that forms a right angle with a line containing the base
hypotenuse
The side opposite the right angle in a right triangle
image
A shape that results from a transformation of a figure known as the preimage
interior of an angle
The set of all points between the sides of an angle
leg
One of the two sides of the right triangle that form the right angle
length
The distance between the two endpoints of a segment
line
A undefined term in geometry, it has no thickness and extends forever
linear pair
A pair of adjacent angles whose non-common sides are opposite rays
midpoint
The point that divides a segment into two congruent segments
obtuse angle
An angle that measures greater than 90 degrees and less than 180 degrees
opposite rays
Two rays that have a common endpoint and form a line
perimeter
The sum of the side lengths of a closed plane figure
pi
The ratio of the circumference of a circle to its diameter
plane
An undefined term in geometry, it is a flat surface that have no thickness and extends forever
point
An undefined term in geometry, it names a location and has no size
postulate
A statement that is accepted as true without proof
preimage
The original figure in a transformation
A segment whose endpoints are the center of a circle and a point on the circle; the distance from the center of a circle to any point on the circle
ray
A part of a line that starts at an endpoint and extends forever in one direction
reflection
A transformation across a line, called the line of reflection
right angle
An angle that measures 90 degrees
rotation
A transformation about a point P, also known as the center of rotation, such that each point and its image are the same distance from P
segment
A part of a line consisting of two endpoints and all points between them
segment bisector
A line, ray, or segment that divides a segment into two congruent segments
straight angle
An angle that measures 180 degrees
supplementary angles
Two angles whose measures have a sum of 180 degrees
transformation
A change in the position, size, or shape of a figure or graph
translation
A transformation that shifts or slides every point of a figure or graph the same distance in the same direction
undefined term
A basic figure that is not defined in terms of other figures
vertex
The common endpoint of the sides of the angle
vertical angles
The nonadjacent angles formed by two intersecting lines