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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

  1. Make a rough sketch of the triangle
  2. Draw the line BC =6cm
  3. Place the centre of the protractor at B. Read the inner scale on the right mark and draw angle 62o
  4. Use your ruler to draw a line BX through angle B.
  5. On BX, measure BA = 4cm and join AC
  6. Measure AC = 5.4cm

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