April 10, 2023
Drawing triangles and other shapes
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1. Drawing triangles
April 10, 2023
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The angle of 40º is called the included angle, as it lies between the two lines of which you know the length.
A B15cm
20cm
40º
CSometimes you are asked to make an accurate drawing of a sketch such as this…You need a pencil, a protractor and a ruler.
Draw and label line A to B , using your ruler.Using a protractor, mark a point at 40º to this line.Using your ruler, draw a line from point A, through the point at 40º.Mark the point 20cm along this line and label it point C.Draw a line joining point B to C, using your ruler.Label the 40º angle and the line AC.
A B15cm
20cm
40º
C
Explanation
April 10, 2023
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The completed triangle.Draw a line longer than PQ.Measure the angle 28º at Q.
12 cm
R
P Q28º35º
Sometimes you are given one side and two angles, like this…
P Q12cm
35º
R
28ºAgain you need a pencil, a protractor and a ruler.Draw and label the line PQ.Measure the angle 35º at P.Draw the line QR.
Explanation
April 10, 2023
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9 cm13 cm
14 cm
Construct a triangle ABC with AB = 14 cm, AC 9 cm and BC = 13 cm.
A B
C
ExplanationYou may be given the length of three sides, but no angles.
This time you will need a pencil, a ruler and a pair of compasses.
April 10, 2023
Z
You may be given two sides and a non-included angle. That is an angle not between the two known sides.
X Y8.6cm
60º
Z
10cm
8.6 cmX60º
Y
10 cm10 cm
Draw the line XY.Measure the angle 60º from X.Draw a line longer than XY.Draw an arc with radius 10 cm from Y.Where the arc crosses the line is Z.Join Y to Z.The completed triangle.
Explanation
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