GR 9 3-5-3 LEARNERS
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NAME:
Gr 9
Date:
Time ½ hr.
CAPS
3-5 Construction of Geometric Figures 3 Construction of
Reference angles of 60° and 30°
3-5-3 Construction of angles of 60° and 30°
Topic
1.
Think First! [5 mins]
1.1
1.2
1.3
1.4
1.5
What geometric 2D shape do you think of when you have 60°
Explain why you chose the shape you did.
Use your compass and ruler to draw an equilateral triangle.
How could you use this construction to create an angle of 60°?
How could you use the construction of a 60° angle to construct an angle of 30°?
2.
Go ahead! [10 mins]
2.1.
2.2
2.3
Construct an angle of 60°.
Bisect your angle of 60°
Construct an equilateral triangle.
Bisect all the angles of the triangle
3.
Check your work! [5 mins]
Measure the angles you have constructed with a protractor, to see that they are accurate.
4.
Go ahead! [10 mins]
4.1
4.2
Construct a triangle with the two base angles each 30°.
Calculate the size of the third angle. How do you know?
5.
Going further! [5 mins + own time]
5.1
What other acute angles could you draw starting with a right angle and an angle of 60°?
5.2
Construct these angles using only a pencil, compass and ruler.
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