Download 2.1.1 Powerpoint

Warm up
1. What is the name of this
shape?
Find the area and
3 cm perimeter.
Rectangle
A = 31.5 sq cm
P = 27 cm
10.5 cm
2. This shape
is a rhombus.
Its perimeter is
80 units. What
is the length of
each side?
18 inches
8 in.
x+7
2x + 3
3. Find the length of each of
the given sides then find the
perimeter & area.
P = 50 in.
10 inches
x=4
A = 112 in2
Each side = 11 inches
7
3
3
20 units
5
3
4. Find the perimeter
and area.
A = 107 sq units
3
P = 48 units
Vocabulary
Complementary angles – TWO
angles whose measures have a
sum of 90°
Supplementary angles – TWO
angles whose measures have a
sum of 180°
30°
A
B
C
60°
D
80°
100°
Vertical angles – when 2 lines (or
segments) intersect, 4 angles
are formed. The pair that are
across the vertex from each
other are called vertical angles
AND they are congruent.
E
~
E = F
F
Geometry Notation
(secret geometry code)
Geometric
item
Point
Line
Looks
like
Labeled
l
A
Plane
A or
point A
.A
.
B
line l
AB or AC or BC or BA
or CA or CB
C
L
M
R
N
Notation
Z
plane LMN
or R
More notation
Geometric
item
Looks
like
Labeled
Notation
line
segment
______
______
AB or BA
A
B
1
angle
1
A
A
XYZ or ZYX
Vertex MUST be
X
Y
Z
Linear Pair
A pair of angles that make a line
mA + mB = 180°
A
B
180 – 152 = mB
152°
134°
3x - 4
46°
x
B
28 = mB
3x – 4 + x = 180
4x – 4 = 180
4x = 184
X = 46
Find the measures of all the angles
Vertical Angles/Linear pair combo
2x – 4 + x = 180
118.6°
2x - 4
61.3°
118.6°
x 61.3°
X = 61.333
Just for fun…
How would you set this one up?
4x – 5 = 3x + 2
4x - 5
3x + 2
Solve and find the
measure of each angle
X=7
Each angle = 23°
Transversal
When 2 lines are intersected by another line,
that ‘other line’ is called a TRANSVERSAL.
How many angles
are there?
none
Let’s look at
this closer…
Now, how
many angles
are there?
8
These 8 angles are a pretty big deal to us!!!
INTERIOR
–The space INSIDE the 2 lines
interior
EXTERIOR
-The space OUTSIDE the 2 lines
exterior
exterior
Special Angle Pairs
Interior Angles
1
3 4
2
<3 & <6 are Alternate Interior angles
<4 & <5 are Alternate Interior angles
<3 & <5 are Same Side Interior angles
<4 & <6 are Same Side Interior angles
5 6
7 8
Exterior Angles
<1 & <8 are Alternate Exterior angles
<2 & <7 are Alternate Exterior angles
<1 & <7 are Same Side Exterior angles
<2 & <8 are Same Side Exterior angles
Special Angle Relationships
WHEN THE LINES ARE
PARALLEL
1
3
5
2
4
6
7 8
If the lines are not
parallel, congruency
DOES NOT EXIST.
♥Alternate Interior Angles
are CONGRUENT
♥Alternate Exterior Angles are
CONGRUENT
♥Same Side Interior Angles are
SUPPLEMENTARY
♥Same Side Exterior Angles are
SUPPLEMENTARY
Assignment
Pg 77; 8 - 11
Back to 2.1.2 &
2.1.3 powerpoint
Let’s Practice
120°1
60°3
120° 5
7
60°
2 60°
4 120°
6 60°
8 120°
m<1=120°
Find all the remaining
angle measures.