Geometry Terms - chapter 1 Flashcards
acute angle
an angle measuring more than 0 degrees and less than 90 degrees
adjacent angles
two angles in the same plane with a common vertex and a common side, but no 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 nonoverlapping unit squares of a given size that will exactly cover the interior of a plane figure
base of a triangle
any side of the triangle
between two points
point B is between points A and C if and only if all three points lie on the same line, and AB + BC = AC
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
segments that have the same length
construction
creating a precise figure, using only a compass and straightedge
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 (x-axis) and a vertical line (y-axis)
coplanar
points that lie in the same plane
degree
a unit of angle measure that is 1/360th of a circle
diameter
a segment with endpoints on a circle and passing through the center of the circle
distance between two points
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 all points outside an angle
height of a triangle
a segment from a vertex that forms a right angle with a line containing the base
hypotenuse
the side opposite the right angle in a right triangle
image
the shape resulting 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 of a right triangle
one of the two sides of a right triangle that form the right angle
length
the distance between the two endpoints of a segment
line
an undefined term; a line is a straight path that has no thickness and extends forever
linear pair
a pair of adjacent angles whose noncommon sides are opposite rays
measure of an angle
the number of degrees that an angle contains
midpoint
the point that divides a segment into two congruent segments
obtuse angle
an angle measuring more 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; it is a flat surface that has no thickness and extends forever
point
an undefined term; 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
radius
a segment whose endpoints are the center of a circle (or sphere) and a point on the circle (or sphere)
ray
a part of a line that starts at an endpoint and extends forever in one direction
reflection
a transformation across a line (line of reflection) such that the line is the perpendicular bisector of every segment joining each point and its image
right angle
an angle measuring 90 degrees
rotation
a transformation about a point P (center of rotation) such that every point and its image are the same distance from P and all of the angles with vertex P formed by each point and its image are congruent
segment (line segment)
part of a line consisting of two points (endpoints) and all of the points between them
segment bisector
a line, ray, segment, or plane that divides a segment into two congruent segments
straight angle
an angle measuring 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
translation
a transformation that shifts or slides every point of a figure the same distance and the same direction
undefined term
a basic geometric figure that is not defined in terms of other figures
vertex of an angle
the common endpoint of the sides of an angle
vertical angles
the nonadjacent angles formed by two intersecting lines
