GEOMETRY CHAPTER 2
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- MIDPOINT
-
a point M is the midpoint of line segment STif and only if M is between S and T and
SM = MT -
postulate 2-4
COMPLETENESS PROPERTY FOR POINTS IN THE PLANE (FOR GRAPH) -
FOR EACH POINT IN A COORDINATE PLANE CORRESPONDS TO ONLY ONE ORDERED PAIR (X,Y)
OF REAL NUMBERS. AND EACH ORDERED PAIR OF REAL NUMBERS CORRESPONDS TO ONE POINT ON THE COORDINATE PLANE. -
postulate 2-1
THE NUMBER LINE POSTULATE -
each real number corresponds to one and only one point on the number line. Each point on the number line corresponds to 1 real number!
-
SYMMETRIC PROPERTY of equality
for real numbers -
for any numbers a and b
if a=b then b=a
9each side looks like a mirror image of the other side) -
REAL numbers
-
includes RATIONAL and
IRRATIONAL numbers -
postulate 2-2
DISTANCE POSTULATE -
for any two points on a number line and a given unit of measure, there is a unique positive real number called the MEASURE of distance between the 2 points
-
THEOREM 2-6
MIDPOINT FORMULA FOR A COORDINATE PLANE -
x one + x two
-----------------
2
and
y one + y two
______________-__
2 -
REFLEXIVE PROPERTY of equality for real numbers
-
for any number a
then:
a=a -
MULTIPLICATION AND DIVISION
PROPERTIES of equality for real numbers -
for any numbers: a, b, and c
if a x c = b x c mult
and if c is not equal to zero
if a/c = b/c division(can't
have 0 in denomin
-
congruence of line segments is
symmetric - SEE PAGE 63
- TRANSATIVE PROPERTY of equality for real numbers
-
for any numbers (can be more than 3) a, b, and c if
a=b and b=c then a=c
-
CONGRUENT SEGMENTS
-
two segments are congruent if and only if they have the same
length -
Congruence of line segments is REFLEXIVE
-
see pg 63
-
VECTOR
-
a DIRECTED line segment if shows movement is a certain direction.
Magnitude=length of vector.
arrowhead=direction of vector -
ADDITION AND SUBTRACTION of
equality for real numbers -
for any numbers a, b, and c
if a=b
then;
a+c=b+c and addition
a-c=b-c subtraction -
postulate 2-3
RULER POSTULATE
- the points on a line can be pared with the real numbers so that the measure of the distance between corresponding points is the positive (absolute value) distance of the 2 numbers
- PRECISION OF MEASUREMENT
-
depends on the smallest unit of measure being used eg 1/16 in. GREATEST POSSIBE ERROR IS
ONE-HALF THE SMALLEST UNIT OF
MEASURE (EG 1/2OF 1/16 OR 1/32 INCH) -
congruence of line segments is
TRANSATIVE - see page 63
-
MEASUREMENTS
-
measurements such as 10 inches
are composed of 2 parts
10 (the number of units)
inches(the unit of measure)
check to include the U of M -
RATIONAL numbers
-
any number written as a/b
wher a and b are intergers (whole numbers) and
b is not zero ************* -
definition of BETWEENNESS
-
3 COLINNEAR POINTS
IF R IS BETWEEN POINT P AND POINT Q THEN:
PR + RQ = PQ -
theorm 2-5
MIDPOINT FORMULA FOR A NUMBER
LINE -
A+B
_________
2 - IRRATIONAL numbers
-
decimals that to not end and do not repeat
example
0.66666666 etc
or pi 3.141 etc - THEORM 2-4
-
IF a and b are real numbers, a vertical line contains all points (x,y)such that x=a and a horizontal line contains all points (x,y) suth that y=b
the equation of a vertical line is x=a and
the equation of a horizontal line is y=b -
COORDINATE of a line
- the NUMBER that corresponds to the point (address) on the line
- WHOLE numbers
-
includes zero and the counting numbers
- SUBSTITUTION PROPERTY of equality for ral numbers
-
for any numbers a and b
if a=b then a may be replaced by b in any equation
(you can substitute one for the other)