undefined terms
A basic figure that is not defined in terms of other figures. The undefined terms in geometry are point, line, and plane.
point
An undefined term in geometry, it names a location and has no size.
line
An undefined term in geometry, a line is a strait path that has no thickness and extents forever.
plane
An undefined term in geometry, it is a flat surface that has no thickness and extends forever.
collinear
points that lie own the same line
coplanar
points that lie in the same plane
segment
is the part of a line consisting of two points and all points between them
endpoint
is a point at one end of the 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
a statement that is accepted as true without proof
coordinate
a pair of numbers used to determine the position of a point on a graph
distance
the amount of space between two points
length
the distance between two points
congruent segments
segments that have the same length
construction
A way of creating a figure that is more precise.
between
a point that lies on the same line but is not one of the end segments
midpoint
a point that divides a segment into two congruent segments
bisects
dividing in half at the midpoint
segment bisector
A segment, ray, line, or plane that intersects a segment at its midpoint
angle
two rays with a common endpoint
vertex
The common endpoint of an angle
interior of an angle
The set of all points between the sides of an angle.
exterior of an angle
the set of all points outside an angle.
measure
how much there is of something that you can quantify
degree
A unit for measuring angles
acute angle
90>angle
right angle
90=angle
obtuse angle
90<angle
strait angle
180=angle
congruent angles
angles of the same degree
angle bisector
a ray that divides an angle into two congruent angles
adjacent angles
two angles that share a common vertex and side, but have no common interior points
linear pair
two adjacent angles whose noncommon sides are opposite rays
complementary angles
two angles whose sum is a right angle
supplementary angles
Two angles whose sum is 180 degrees
vertical angles
a pair of opposite congruent angles formed by intersecting lines
perimeter
the size of something as given by the distance around it
area
the measure of space within a boundary
base
a flat bottom on which something is intended to sit
height
how tall something is
diameter
the distance across a circle through its center
radius
a straight line from the center to the perimeter of a circle (or from the center to the surface of a sphere)
circumference
the distance around a circle
pi
The numerical value of the ratio of the circumference of a circle to its diameter of approximately 3.14159.
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.
leg
the two sides that form the right angle of a right triangle
hypotenuse
the side of a right triangle opposite the right angle
transformation
the change in position, size, or shape of a figure
preimage
the original figure
image
figure that results for a transformation
reflection
A transformation of a figure that flips the figure across a line.
rotation
the act of rotating as if on an axis
translation
the act of uniform movement