1-2 measuring and constructing segments 2AB.notebook

1­2 measuring and constructing segments 2AB.notebook
February 05, 2014
When solving equations with variable on both sides
3 cases for solutions
I. Solution ⇒ x = ­3
II. No Solution ⇒ variables cancel out
ex. 5 = 11
III. ALL Real #'s ⇒ reflexive property
ex. 3x = 3x
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1­2 measuring and constructing segments 2AB.notebook
February 05, 2014
Math Humor
Carpenter 1: Why did you leave your tape measure in the truck?
Carpenter 2: Because we’re entering a construction zone.
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1­2 measuring and constructing segments 2AB.notebook
February 05, 2014
Objective: Use length and midpoints of segments
construct midpoints and congruent segments
Postulate
l­2­1 Ruler Postulate
for every pt on a line there
is one # associated with the point
example
ruler
0
1
2
3
4
5
0°
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
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1­2 measuring and constructing segments 2AB.notebook
February 05, 2014
Objective: Use length and midpoints of segments
construct midpoints and congruent segments
R
E
C
A
L
L
segment
part of a line with 2 endpts and include all point between
diagram
A
B
notation
Symbol
words
Segment AB
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1­2 measuring and constructing segments 2AB.notebook
February 05, 2014
Objective: Use length and midpoints of segments
construct midpoints and congruent segments
coordinate number associated with a point
example
A
­6
B
­5
­4
­3
­2
­1
0
1
2
coordinate of A is ­ 5 and the coordinate of B is 1
distance
(between pts on a segment)
­ subtract coordinates and take absolute value
***
notation
REMINDER ­ distance is ALWAYS POSITIVE
just the letter of the points
⇒ AB (is a number)
example:
***
the distance from A to B is 6 units
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1­2 measuring and constructing segments 2AB.notebook
February 05, 2014
Objective: Use length and midpoints of segments
construct midpoints and congruent segments
length
the distance from one point to another
example:
figure ­ can't have a length
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1­2 measuring and constructing segments 2AB.notebook
February 05, 2014
Objective: Use length and midpoints of segments
construct midpoints and congruent segments
Congruent
Same SHAPE and size
notation
example
Shape
REMINDER
number ­ can perform operations with AB and CD
Congruent
Segments
Segments w/ same length
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1­2 measuring and constructing segments 2AB.notebook
February 05, 2014
Objective: Use length and midpoints of segments
construct midpoints and congruent segments
construct
use geometric tools to reproduce a figure
Construction figure created using geometric tools
recognized
⇒
arcs on the figure
straightedge any object that makes a straight line
compass
instrument for drawing circles and arcs
and measuring distances between points
has of two arms linked by a movable joint
one arm ending in a point
the other usually carrying a pencil or pen.
arc
portion of circle
example
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1­2 measuring and constructing segments 2AB.notebook
February 05, 2014
Objective: Use length and midpoints of segments
construct midpoints and congruent segments
Construct
Congruent
Segments
STEPS
1) Draw a line
(LONGER THAN GIVEN SEGMENT)
2) Label a point on the line
3) Place pointed end of compass
on one endpt of given segment
4) Extend compass so pencil is on
2nd endpt of given segment
5) DO NOT ADJUST compass
Place pt of compass on pt on line
6) Make an arc on the line
7) Put a pt where arc intersect line
8) Label 2nd pt on the line
**** Verify segments are congruent using ruler
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1­2 measuring and constructing segments 2AB.notebook
February 05, 2014
Objective: Use length and midpoints of segments
construct midpoints and congruent segments
Construct
Congruent
Segments
B
A
line
41°
144
AB =
CD =
****
Verify segments are congruent by measuring them
ruler
0
1
2
3
4
5
0°
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
­ study notes
­ finish worksheet construct #'s 2 & 3
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