Construction Of Triangles

Please remember that these aren’t the only way of constructing triangles, there are numerous other ways. I strongly encourage you to experiment and explore different ways of constructing, because learning doesn’t start and end at the classrooms… Good luck and have fun experimenting. Cheers, Pedup

Note: These notes haven’t been properly referenced because it was originally collected for personal use while teaching you guys. So, please don’t cite anything and if you have access to internet then you may get these notes online from my blog http://pedupsobservationalexperience.blogspot.com (I shall post it, ASAP) I didn’t get much time to work on the notes, so it may not be intelligent and coherent, if you have anything to say or comment, please feel free to do so in the comment section of my blog. I shall read your comments/ suggestion, consider it and implement the necessary change. Thank you.

Construction of an equilateral triangle: Method 1: When you are given one side length

Method 2: When no side length is given (i.e. no information is given)

Method 3: When you are given one side length Given the line segment extending from point A to point B, carry out the following steps to construct an equilateral triangle with base AB.

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Step 1: Construct a circle of radius AB at the point A.

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Step 2: Construct a circle of radius AB at the point B.

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Step 3: Connect points A and B to one of the points of intersection of the two circles.

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You're done! Triangle ABE is an equilateral triangle.

Construction of a right angled triangle in a circle: (i.e. when no information is given)

Construction of a Triangle given the lengths of 3 sides (i.e. SSS) Given the lengths of three sides AB, AC, and BC, carry out the following steps to construct Triangle ABC. •

Step 1: Construct a line segment of length AB.

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Step 2: Construct a circle of radius AC at the point A.

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Step 3: Construct a circle of radius BC at the point B. Label one of the intersection points C.

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Step 4: Connect the points A, B, and C with line segments.

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You're done! Triangle ABC has been constructed from the given sides.

Constructing a Triangle given Two Angles and the Side between them Solution:

Constructing a Triangle given Two Sides and an Angle

Solution:

Constructing a Triangle given Two Sides and the Angle between them

Solution: Step 1: Step 2: Step 3: Step 4:

Draw a line, AB, 9 cm long. Mark an angle of 70º by placing the centre of the protractor at the point A. Join the 70º mark and the point A. Extend the arm AC until it is 7 cm long. Join the points B and C to obtain the required triangle ABC.

Practice problem for you to do: (Good Luck doing it)