Geometry Terms

Front 1

The protractor postulate
(postulate 9)

Back 1

In a half plane with the edge AB and any point S between A and B, there exists a one-to-one correspondence between the rays that originate at S in that half plane and the real number between 0 and 180. To measure an angle formed by two of these rays, find the absolute value of the difference of the corresponding real numbers.

Front 2

Alternate interior angles

Back 2

a pair of non adjacent angles , both interior, on opposite side of the transversal

Front 3

postulate 5

Back 3

* If two distinct planes intersect then their intersection is a line

Front 4

unique

Back 4

meaning exactly one or one

Front 5

Linear Pair postulate
(postulate 10)

Back 5

If two angles form a linear pair, then they are supplementary angles.

Front 6

parallel planes

Back 6

two planes are parallel iff they do not intersect

Front 7

Postulate 3

Back 7

* through any two points there are infinitely many planes.
* Through any three points there is at least one plane
* Through any three noncollinear points there is exactly one plane

Front 8

half plane

Back 8

two halfs of plane that are seperated by a line

Front 9

Concave

Back 9

if any lines of the polygon do contain interior points, the polygon is called concave,

Front 10

polygons

Back 10

a polygon consists of three or more coplaner segments; the segments, sides, intersect only at the endpoints; each endpoint, vertex belongs to exactly two segments; no two segments with a common endpointare collinear

Front 11

Postulate 4

Back 11

* If two points are in a plane, then the line that contains those points lies entirely in the plane

Front 12

between

Back 12

given three collinear points x,y,z, y is between x and z iff xy+yz=xz

Front 13

postulate 6

Back 13

* given any two points there is a unique distance between them

Front 14

convex

Back 14

a polygon is convex iff the lines containg teh sides do not contain points in the polygon interior

Front 15

Postulate 1

Back 15

* a line contains at least two distinct points
* A plane contains at least three noncollinear points
* Space contains at least four noncollinear points

Front 16

Point

Back 16

has no size or dimension, merely a position indicator. Points are names by upper case letters.

Front 17

regular polygon

Back 17

a polygon is a regular polygon iff it is both equilateral and equilangular

Front 18

parallel segments or rays

Back 18

segments or rays are parallel iff the lines that contain them are parallel

Front 19

Postulate 2

Back 19

* Two distinct points determine a unique line

Front 20

ray

Back 20

set of points that consists of a segment

Front 21

The Ruler Postulate
(postulate 7)

Back 21

There is a one-to-one correspondence between the points of a line and the set of real numbers such that the distance between two distinct points of the line is the absolute valuse of the difference of their coordinates

Front 22

linear pair

Back 22

adjacent angles whose noncommon sides are opposite rays

Front 23

Diagonal

Back 23

a diagonal of a polygon is a segment that joins two nonconsecutive vertices of the polygon.

Front 24

intersection

Back 24

the set of points that lie in both figures

Front 25

postulate 8

Back 25

* Given any angle there is a unique real number between 0 and 180 known as its degree measure

Front 26

Triangle

Back 26

a set of points is a triangle iff is consists of the figure formed by three segments vonnevting three noncollinear point

Front 27

plane

Back 27

a flat surface with no defined thickness that extends without end in all directions. Usually pictured as a four sided figure. Named with a Capitol letter or with any thre non collinear points.

Front 28

vertical angles

Back 28

two nonadjacent angles formed by two intersecting lines

Front 29

space

Back 29

the set of all points

Front 30

perpendicular bisector of a segment

Back 30

Line, ray segment, or plane that is perpendicular to a segment at its midpoint

Front 31

postulate

Back 31

statement accepted as true

Front 32

interior angles

Back 32

angles inside the lines being transversed

Front 33

Theorem

Back 33

statement that must be proven true

Front 34

scalene

Back 34

no congruent sides

Front 35

segment

Back 35

set of points on a line that consists of two points

Front 36

Supplementary angles

Back 36

Iff their sum=180

Front 37

line

Back 37

consists of an infinate number of points, and extends in both directions without end. Name lines with 2 points from the line or with a lower case letter.

Front 38

corollary

Back 38

theorem whose justification follows from another theorem

Front 39

measure

Back 39

distance between the endpoints of the segment

Front 40

obtuse triangles

Back 40

one obtuse angle

Front 41

congruent

Back 41

segments having equal measures

Front 42

perpendicular

Back 42

two lines that intersect to form right angles

Front 43

right triangles

Back 43

on right angle

Front 44

auxiliary line

Back 44

lines, segments, rays or points added to a figure in order to facilitate a proof or an understanding of a problem. Their introduction must be justified by a postulate or theorem

Front 45

equilangular

Back 45

three congruent angles

Front 46

equilateral

Back 46

all sides congruent

Front 47

Parallel lines

Back 47

two lines are parallel iff they lie in the same plane and do not intersect

Front 48

bisector

Back 48

any line, segment, ray or plane that intersects a segment at its midpoint

Front 49

exterior angles

Back 49

angles outside the lines being transversed

Front 50

adjacent

Back 50

(next to) have to have a common side, common vertex, no interior points

Front 51

corresponding angles

Back 51

a pair of nonadjacent angles, one interior, one exterior, both on the same side of the transversal

Front 52

skew lines

Back 52

twon lines are skew iff they do not lie in the same plane and do not intersect

Front 53

Complementary angles

Back 53

Iff their sum=90

Front 54

vertex

Back 54

common endpoints of an angle

Front 55

midpoint

Back 55

point that divides a segment into two congruent segments

Front 56

isosceles

Back 56

two sides congruent

Front 57

acute triangles

Back 57

three acute angles

Front 58

angle

Back 58

the union of two noncollinear rays

Front 59

alternate exterior angles

Back 59

a pair of non adjacent angles, both exterior, on opposite sides of the transversal

Front 60

Tranversal

Back 60

a line is a transversal iff it intersects two or more coplaner lines at different points