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Angle Properties
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MTH 3-17a
Revision of Level E
Interior / Exterior Angles
Angles in Time
30-Apr-17
Created by Mr. Lafferty
Starter Questions
MTH 3-17a
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1.
Calculate the volume of the following shapes.
5 cm
3 cm
Q2. Find 3.5% of £200.
10 cm
3 cm
Q.3 Calculate
(a)
30-Apr-17
- 6 - (7 - 8)
(b) (-10) x (-3)
Created by Mr. Lafferty
(c) (-2) x (-12)  4
Angle Properties
Revision of Level E
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MTH 3-17a
Learning Intention
Success Criteria
1. We are reviewing angle
properties.
1. Remember basic properties
for angles.
2. Apply properties to solve
angle problems..
30-Apr-17
Created by Mr. Lafferty
Angle Properties
Revision of Level E
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MTH 3-17a
o
120 95
115
o
Angles round a point
o
Add up to 360
34
o
34
146o
50
90o
o
angles opposite each other
at a cross are equal.
30-Apr-17
65o
Two angles making a
o
straight line add to 180
145o
146o
o
o
40
o
3 angles in a triangle ALWAYS
o
add up to 180 .
Created by Mr. Lafferty
Angle Properties
Revision of Level E
www.mathsrevision.com
MTH 3-17a
Two angles in a isosceles
Are equal
h
b
c
e
ALL angles in an equilateral
o
triangle are 60
is corresponding to d and must be 115
is opposite to d and must be 115
o
o
is alternate to c and must also be 65
30-Apr-17
Created by Mr. Lafferty
c
o
h
o
is must be 65 (straight line)
d = 115
o
g
o
o
o
a
o
o
b
o
e
f
o
Angle Properties
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Revision of Level E
Now try Exercise 1
Ch3 (page 21)
Copy out shapes
30-Apr-17
Created by Mr. Lafferty
Starter Questions
MTH 3-17a
www.mathsrevision.com
1.
Calculate the volume of the following shapes.
7 cm
3 cm
Q2. Find 5.5% of £300.
20 cm
5 cm
Q.3 Calculate
(a)
- 4 - (17 - 6)
30-Apr-17
(b) (-8) x (-8)
Created by Mr. Lafferty
(c) (-3) x (-20)  4
Polygons
Interior and Exterior Angles
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MTH 3-17a
Learning Intention
Success Criteria
1. We are exploring interior
and exterior angles of a
polygon .
1. To know the term polygon.
2. Understand steps for
calculating the interior and
exterior angle of a polygon.
30-Apr-17
Created by Mr. Lafferty
Polygons
Interior and Exterior Angles
MTH 3-17a
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A polygon is a “many-sided closed straight-lined figure”
This 5-sided (polygon) is called a PENTAGON
Irregular Pentagon
30-Apr-17
Created by Mr. Lafferty
Polygons
Interior and Exterior Angles
MTH 3-17a
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A polygon is a “many-sided closed straight-lined figure”
If all the sides and angles are the same it is called
REGULAR POLYGON. We will only be dealing with
regular polygons in this section.
Pentagon
30-Apr-17
Hexagon
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Octagon
Polygons
Interior and Exterior Angles
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MTH 3-17a
Some useful points about regular polygons :
•
All the triangles around the centre are isosceles.
•
Angle at the centre is 360o
•
To find one angle at the centre, take 360o and
divide it by how many triangles you have
72o
Pentagon
Interior Angle
30-Apr-17
60o
Hexagon
Created by Mr. Lafferty
45o
Octagon
Interior Angles
Level F - Polygons Worksheet Ex2
Pentagon (5 sided)
Hexagon (6 sided)
Heptagon (7 sided)
Octagon (8 sided)
Nonagon (9 sided)
Decagon (10 sided)
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MTH 3-17a
30-Apr-17
Created by Mr. Lafferty
Polygons
Interior and Exterior Angles
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MTH 3-17a
Now try Exercise 2
Ch3 (page 23) Q1-Q6
Use worksheet Provide
30-Apr-17
Created by Mr. Lafferty
Polygons
Interior and Exterior Angles
MTH 3-17a
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What you should have found :
Polygon sides
Sum of Angles
4
5
6
7
8
9
11
12
360 540 720 900 1080 1260 1440 1620 1800
Size of Interior Angle 90 108 120 129 135
Interior angle = 180 – (360÷n)
140
Interior angle = 180 – (360÷6) = 120o
Created by Mr. Lafferty
144
149
150
n = Number of sides
eg . A hexagonal has interior angle is:
30-Apr-17
10
Polygons
Interior and Exterior Angles
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MTH 3-17a
A
E
B This is called the
“Exterior angle”
O
Pentagon
D
C
Q
Exterior angle = 180 – interior angle
eg . For the pentagon above :
Exterior angle = 180 – 108 = 72o
30-Apr-17
Created by Mr. Lafferty
Polygons
Interior and Exterior Angles
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MTH 3-17a
Now try Exercise 2
Ch3 (page 23) Q8-Q9
Use worksheet Provide
30-Apr-17
Created by Mr. Lafferty
Starter Questions
MTH 3-17a
www.mathsrevision.com
1.
Calculate the volume of the following shapes.
10 cm
4 cm
Q2. Find 7.5% of £600.
7 cm
3 cm
Q.3 Calculate
(a)
30-Apr-17
- 6 + (23 - 5)
(b) (-15) x (-10)
Created by Mr. Lafferty
(c) (-32) x (-4)  4
Polygons
Interior and Exterior Angles
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MTH 3-17a
Practice on Angles
Now try Exercise 3
Ch3 (page 26)
30-Apr-17
Created by Mr. Lafferty