Geometry Terms - chapter 1

Question 1

acute angle

Answer 1

an angle measuring more than 0 degrees and less than 90 degrees

Question 2

adjacent angles

Answer 2

two angles in the same plane with a common vertex and a common side, but no common interior points

Question 3

angle

Answer 3

a figure formed by two rays with a common endpoint

Question 4

angle bisector

Answer 4

a ray that divides an angle into two congruent angles

Question 5

area

Answer 5

the number of nonoverlapping unit squares of a given size that will exactly cover the interior of a plane figure

Question 6

base of a triangle

Answer 6

any side of the triangle

Question 7

between two points

Answer 7

point B is between points A and C if and only if all three points lie on the same line, and AB + BC = AC

Question 8

bisect

Answer 8

to divide into two congruent parts

Question 9

circumference

Answer 9

the distance around a circle

Question 10

collinear

Answer 10

points that lie on the same line

Question 11

complementary angles

Answer 11

two angles whose measures have a sum of 90 degrees

Question 12

congruent angles

Answer 12

angles that have the same measure

Question 13

congruent segments

Answer 13

segments that have the same length

Question 14

construction

Answer 14

creating a precise figure, using only a compass and straightedge

Question 15

coordinate

Answer 15

a number used to identify the location of a point

Question 16

coordinate plane

Answer 16

a plane that is divided into four regions by a horizontal line (x-axis) and a vertical line (y-axis)

Question 17

coplanar

Answer 17

points that lie in the same plane

Question 18

degree

Answer 18

a unit of angle measure that is 1/360th of a circle

Question 19

diameter

Answer 19

a segment with endpoints on a circle and passing through the center of the circle

Question 20

distance between two points

Answer 20

the absolute value of the difference of the coordinates of the points

Question 21

endpoint

Answer 21

a point at an end of a segment or the starting point of a ray

Question 22

exterior of an angle

Answer 22

the set of all points outside an angle

Question 23

height of a triangle

Answer 23

a segment from a vertex that forms a right angle with a line containing the base

Question 24

hypotenuse

Answer 24

the side opposite the right angle in a right triangle

Question 25

image

Answer 25

the shape resulting from a transformation of a figure known as the preimage

Question 26

interior of an angle

Answer 26

the set of all points between the sides of an angle

Question 27

leg of a right triangle

Answer 27

one of the two sides of a right triangle that form the right angle

Question 28

length

Answer 28

the distance between the two endpoints of a segment

Question 29

line

Answer 29

an undefined term; a line is a straight path that has no thickness and extends forever

Question 30

linear pair

Answer 30

a pair of adjacent angles whose noncommon sides are opposite rays

Question 31

measure of an angle

Answer 31

the number of degrees that an angle contains

Question 32

midpoint

Answer 32

the point that divides a segment into two congruent segments

Question 33

obtuse angle

Answer 33

an angle measuring more than 90 degrees and less than 180 degrees

Question 34

opposite rays

Answer 34

two rays that have a common endpoint and form a line

Question 35

perimeter

Answer 35

the sum of the side lengths of a closed plane figure

Question 36

pi

Answer 36

the ratio of the circumference of a circle to its diameter

Question 37

plane

Answer 37

an undefined term; it is a flat surface that has no thickness and extends forever

Question 38

point

Answer 38

an undefined term; it names a location and has no size

Question 39

postulate

Answer 39

a statement that is accepted as true, without proof

Question 40

preimage

Answer 40

the original figure in a transformation

Question 41

radius

Answer 41

a segment whose endpoints are the center of a circle (or sphere) and a point on the circle (or sphere)

Question 42

ray

Answer 42

a part of a line that starts at an endpoint and extends forever in one direction

Question 43

reflection

Answer 43

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

Question 44

right angle

Answer 44

an angle measuring 90 degrees

Question 45

rotation

Answer 45

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

Question 46

segment (line segment)

Answer 46

part of a line consisting of two points (endpoints) and all of the points between them

Question 47

segment bisector

Answer 47

a line, ray, segment, or plane that divides a segment into two congruent segments

Question 48

straight angle

Answer 48

an angle measuring 180 degrees

Question 49

supplementary angles

Answer 49

two angles whose measures have a sum of 180 degrees

Question 50

transformation

Answer 50

a change in the position, size, or shape of a figure

Question 51

translation

Answer 51

a transformation that shifts or slides every point of a figure the same distance and the same direction

Question 52

undefined term

Answer 52

a basic geometric figure that is not defined in terms of other figures

Question 53

vertex of an angle

Answer 53

the common endpoint of the sides of an angle

Question 54

vertical angles

Answer 54

the nonadjacent angles formed by two intersecting lines