## Geometry Vocabulary

##### Created by:

surfergirll  on September 20, 2012

##### Description:

Vocabulary for honors geometry

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# Geometry Vocabulary

 pointa dot; has no dimension, represented by a capital letter
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#### Definitions

point a dot; has no dimension, represented by a capital letter
line extends in two directions without end, one dimension (length) no width or thickness, represented by a single lowercase letter or two points
postulate a statement that is accepted without proof
plane extends in two dimensions (length and width) without ending, has no thickness, often represented as a capital letter
space a collection of all points
collinear points points all in one line
coplaner points points all in one plane
intersect/intersection to meet and cross, to piece or divide, the set of points common to two or more geometric configurations
segment the union of two endpoints and all the points between them
ray consists of a collection of points extending from an endpoint continuing infinity in one direction
opposite rays two rays that share a common endpoint and continuing infinity in one direction
length the absolute value of the difference between two coordinates
coordinate the real number that corresponds to a point
between a geometric concept that implies points are collinear
congruent two objects with exactly the same size and shape
congruent segments two segments of equal length
midpoint of a segment a point which divides a segment into two congruent segments
bisector of a segment a line, ray, segment, or plane that intersects a segment at its midpoint
angle a figure formed by two rays sharing a common endpoint
acute angle any angle whose measure is greater than zero degrees but less than 90 degrees
right angle any angle whose measure is exactly 90 degrees
obtuse angle any angle whose measure is greater than 90 degrees but less than 180 degrees
strait angle any angle whose measure is exactly 180 degrees
congruent angles angles that have equal measure
adjacent angles two angles in a plane that:
1. have a common vertex
2. share a common side
3. have no common interior point
bisector of an angle a ray that divides an angle into two congruent adjacent angles
conditional statement a logical statement that contains two parts, a hypothesis and a conclusion
"if-then" form If hypothesis, then conclusion
hypothesis the premise, the argument, something supposed to be true
conclusion the result, the inference, the outcome
negation the writing of the negative of a statement
converse a statement written by switching the hypothesis and conclusion
inverse formed when you negate the hypothesis and conclusion
contrapositive formed when you negate the converse
equivalent statements formed when two statements are either both true or both false
biconditional statement writing the conditional statement and its converse using the phrase, "if and only if"
counter example formed by finding an example in which the hypothesis is true and the conclusion is false
Addition Proterty of Equality (APOE) if a=b and c=d, then a+c = b+d
Subtraction Proterty of Equality (SPOE) if a=b and c=d, then a-c = b-d
Multiplication Proterty of Equality (MPOE) if a=b, then ac = bc
Division Proterty of Equality (DPOE) if a=b and c(doesn't)=0, then a/c = b/c
Reflexive Proterty of Equality (RPOE) a=a
Symmetric Proterty of Equality (SyPOE) if a=b, then b=a
Transitive Proterty of Equality (TPOE) if a=b and b=c, then a=c
Distributive Proterty of Equality (DiPOE) if a(b +/- c +/- d) then ab +/- ac +/- ad
Reflexive Proterty of Congruence (RPOC) <DE (is congruent to) <DE
Symmetric Proterty of Congruence (SPOC) if <DE (is congruent to) <FG, then <FG (is congruent to) <DE
Transitive Proterty of Congruence (TPOC) if <DE (is congruent to) <FG and <FG (is congruent to) <JK, then <DE (is congruent to) <JK
two column proof contains and column labeled statements and another column labeled reasons
verticle angles two angles with sides that form two pairs of opposite rays, formed by the intersection of two lines
linear pair two adjacent angles if their noncommon sides are opposite rays
complementary angles sum of two measures of angles that equal 90 degrees
supplementary angles sum of two measures of angles that equal 180 degrees
perpendicular lines two lines which intersect to form right angles
parallel lines lines that are coplaner and do not intersect
skew lines lines that are not coplaner and do not intersect (will never be parallel)
parallel planes planes that do not intersect
transversal a line that intersects two or more coplaner lines at different points
corresponding angles two angles that occupy corresponding positions
alternate interior angles two angles that lie inside the two lines on opposite sides of the transversal
alternate exterior angles two angles that lie outside the two lines on opposite sides of the transversal
consecutive interior angles two angles that lie between the two lines on the same side of the transversal
triangle a figure formed by three segments joining three non-collinear points
auxiliary line a line, ray, or segment added to a diagram to help in a proof
corollary a statement that can be proved easily by applying a theorem
exterior angle when one side of a triangle is extended
polygon a figure with many strait sides such that each segment intersects exactly two other segments and no two segments are collinear
convex polygon a plygon such that no line containing a side of the polygon contains a point in the interior of the polygon
concave polygon a polygon such that no line containing a side of the polygon does contain a point in the interior of the polygon
diagnol any segment joining to nonconsecutive vertices
summa sum of, summation
regular polygon any plygon that is both equiangular and equilateral
ratio a comparison of two numbers
(a to b, a:b, a/b, b[does not]= 0)
congruent two figures have exactly the same shape and size
congruent triangles two triangles are congruent if and only if their vertices can be matched up such that the corresponding parts of the triangle are congruent
CPCTC Corresponding Parts of Congruent Triangles are Congruent
2D Name of Polygons 3 triangle
5 pentagon
6 hexagon
7 septagon/heptagon
8 octagon
9 nonagon
10 decagon
11 undecagon
12 dodecagon
20 icosagon
n n-gon

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