Honors Geometry Unit 1 Vocabulary List

Front 1

Acute Angle

Back 1

an angle whose measure is less than 90 degrees

Front 2

Angle

Back 2

a figure formed by two rays with a common endpoint

Front 3

Angle Bisector

Back 3

a line or ray that divides an angle into two congruent angles

Front 4

Center of Rotation

Back 4

the point that every other point moves around in a rotation

Front 5

Collinear Points

Back 5

a single line can contain them all

Front 6

Complementary Angles

Back 6

two angles whose measures have a sum of 90 degrees

Front 7

Conjecture

Back 7

a statement that you think is true- an "educated guess"

Front 8

Coordinate Plane

Back 8

a plane on a coordinate grid

Front 9

Coplanar

Back 9

a single plane can contain them all

Front 10

Endpoints

Back 10

the location where a line/ray begins/ends

Front 11

Glide Reflection

Back 11

a type of composite transformation where a figure is reflected and then translated in a parallel direction

Front 12

Image

Back 12

a shape that has undergone a motion or transformation

Front 13

Line

Back 13

has no thickness, is perfectly straight and extends forever

Front 14

Line Segment

Back 14

part of a line that begins at one point and ends at the other

Front 15

Linear Pair

Back 15

if two angles form this, they are supplementary

Front 16

Midpoint of a Segment

Back 16

the point where a bisector intersects a segment

Front 17

Obtuse Angle

Back 17

an angle whose measure is greater than 90 degrees and less than 180 degrees

Front 18

Parallel Lines

Back 18

two coplanar lines that do not intersect

Front 19

Perpendicular Lines

Back 19

two lines that intersect to form a right angle

Front 20

Plane

Back 20

geometric figure that extends infinitely in all directions along a flat surface

Front 21

Point

Back 21

often shown as dots, represent location and have no size

Front 22

Postulate

Back 22

statements that are accepted as true without proof

Front 23

Pre-image

Back 23

a shape that undergoes a motion or transformation

Front 24

Ray

Back 24

a part of a line that starts at one point and extends infinitely in one direction

Front 25

Reflection

Back 25

geometric figures are flipped across a line, which plays the role of a mirror

Front 26

Right Angle

Back 26

an angle whose measure is 90 degrees

Front 27

Rigid Transformation

Back 27

Transformation that does not change the size or shape of a figure

Front 28

Rotation

Back 28

every point of a figure moves around a given point

Front 29

Segment Bisector

Back 29

a line that divides a segment into two congruent parts

Front 30

Supplementary Angles

Back 30

two angles whose measures have a sum of 180 degrees

Front 31

Transformation

Back 31

mathematical motion

Front 32

Translation

Back 32

every point of a figure moves in a straight line, and all points move the same distance and in the same direction

Front 33

Undefined Terms

Back 33

the building blocks of geometry - lines, planes and points