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WEEK 6
TOPIC: Construction
Content
- (a) Construction of special angles (Revision)
- (b) Constructing triangles
- (i) Two sides and an included angle (ii) Two angles and a side between them. (iii) all the 3 sides
- (c) Bisecting angles: bisecting angle 90, 60 and bisect any given angles.
Construction of Special Angles
A compass, a pencil, a protractor and a ruler are the needed mathematical instruments for this construction. Angles 30o, 45o 60o, 90o and their multiples should be thoroughly revised as a prerequisite for the next stage.
Construction of Triangles
Two sides and an Included Angle: an included angle is an angle holding two sides of the triangle.
Example 1
A protractor, a pencil and a ruler are the needed mathematical instruments for this construction.
Construct a triangle ABC, such that AB = 4cm, BC = 6cm, =62°. Measure AC.
Solution Steps
- Make a rough sketch of the triangle
- Draw the line BC =6cm
- Place the centre of the protractor at B. Read the inner scale on the right mark and draw angle 62o
- Use your ruler to draw a line BX through angle B.
- On BX, measure BA = 4cm and join AC
- Measure AC = 5.4cm
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