were going to grade homework first today please get it out and be ready when the bell rings. thanks
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Measuring LengthTRANSCRIPT
We’re going to grade homework first today
Please get it out and be ready when the bell rings.
Thanks
Measuring
Pick 6 strips of paper from the container. Get a ‘ruler’.
With your partner, please measure and record the measurements of the items you chose from the bucket.
Your measurements need to be as accurate as possible – NOT ESTIMATES.
Measuring Length
How do you measure distance on a number line?
-3 -2 -1 0 1 2 3 4 5 6 7
What is the distance between -2 and 3 5
What is the distance between -2 and -7
What is the distance between 5 and 17
What is the distance between 0 and -5
What is the distance between 10 and -3
5
12
5
13
Notice that all the DISTANCES ARE POSITIVE!
What mathematical operation makes all answers positive?
ABSOLUTE VALUE!!!
♥ On a number line, the distance between the coordinates a and b is |a-b| or |b-a|.
♥ This will give you the measure of the segment.
Measuring length
a b
WRITE THIS DOWN
Notation for MEASURE of a segment
mXY or XY If you use the bar, use the m. If you don’t use the bar, don’t use the m
In this notation, we are talking about the LENGTH of the segment NOT the segment itself.
-3 -2 -1 0 1 2 3 4 5 6 7
X Y Z
mXY = |-3 - 0|
= |-3|
= 3
XZ = |-3 - 4|
= |-7|
= 7
CONGRUENT
• Means the same size and same shape
• The congruent symbol is =~
• Means the same size and same shape
• The congruent symbol is =~
A B C D AB CD ~=
A B
C D
E
Segment Congruence Postulate
♥ If two segments are congruent, then they have the same measure.
♥ The converse is also true :If two segments have the same measure,
then they are congruent.Are you able to write a biconditional?Remember…. A biconditional IS A
DEFINITION
A B
C D
E
~=
• The converse is also true:If AC = BD then AC BD
Important notation• If AC BD then AC = BD~=
•This says: if the segments are CONGRUENT then the measures are EQUAL.
Without the bar means NUMBER
AC is a NUMBER
AC is NOT
Segment Addition Postulate
If point R is between points P and Q, then PR + RQ = PQ
P R Q
A B C
3 5
AB + BC = AC
3 + 5 = AC
8 = AC
X + 3x + 1 = 25
4x + 1 = 25
4x = 24
X = 6
Find the measure of each segment and CHECK YOUR ANSWER
A B C
x 3x + 1 AC = 25
Let’s learn how to BISECTa segment
You need 1 piece of patty paper straight edge compass
Your assignment
2.2/2.3packet