Download Ex 7.2 Angles and Measurements

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Chapter 7:
Angles and Parallel Lines
7.2 Angles
A) Angles and Measurements
We can measure a corner of Louvre Museum in Paris, France.
B
A
Le us name the angle
The unit of angle is degree.
C
Example:
ABC  60
o
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7.2 Angles
B) Types pf Angles
ICT Lesson
Here are more examples types of angles
Complementary angles
A
C
Note:
If the sum of two angles adds up
to 90o
ABC  60
o
ABD  30 o
B
D
ABC  ABD  60  30  90
o
o
o
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WHAT HAVE
YOU LEARNT?
Let us try this
Note:
This is a complementary angle where
the two angles adds up to 90o
x  62  90
o
x  90  62
o
o
o
x  28
o
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WHAT HAVE
YOU LEARNT?
Let us try this…
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PROPERTIES OF ANGLES
D
E
Here
A
B
C
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WHAT HAVE
YOU LEARNT?
Let us try this
AOE  EOD  DOB  180 o
AOE  30 o  90 o  180 o
AOE  60 o
The sum of adjacent angles
on a straight line is 180o.
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Sum of all angles at a point is 360o
Here
63o+ 50o + 75o + 1100 + c = 360o
Therefore
c = 137o
Sum of all angles adds to 360o
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ICT Lesson
When two straight lines intersect, the
vertically opposite angles are equal.
S
P
POQ  SOR  105
POS  POR  75
o
o
o
Reason: Vertically opposite angles.
Q
R
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WHAT HAVE
YOU LEARNT?
Sec One Express Mathematics
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Activity I
Click on the following link to recall the types of
angles.
http://www.mathsisfun.com/angles.html
Ace-Learning Activity
• Log on to your Ace-Learning account and
follow the instructions
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Content Hub -> Exploratory Activities
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Exploratory Activities: Geometry -> Complete these
1 Adjacent angles on a straight line
2 Angles at a point
3 Vertically opposite angles
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Exploratory Activities: Alternate Angles
Explore the following
from Ace-learning
1 Adjacent angles on a
straight line
2 Angles at a point
3 Vertically opposite angles
Follow the activities in this order –
Exploration, Understanding & Application!
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HAVE FUN!
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