Difference between revisions of "Angle sum property of a Triangle"

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=== Objectives ===
 
=== Objectives ===
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* To establish the angle sum property of a triangle
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* To help visualization of the geometric proof
  
 
=== Estimated Time ===
 
=== Estimated Time ===
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30 minutes
  
 
=== Prerequisites/Instructions, prior preparations, if any ===
 
=== Prerequisites/Instructions, prior preparations, if any ===
 +
Prior understanding of point, lines and angles, adjacent angles, vertically opposite angles, linear pair, parallel lines, alternate angles,      corresponding angles.
  
 
=== Materials/ Resources needed ===
 
=== Materials/ Resources needed ===
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** What can you say about the line drawn?
 
** What can you say about the line drawn?
 
** Is it parallel to one of the sides?
 
** Is it parallel to one of the sides?
** What can you say about the pairs of angles – look at the matching colors.
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** What can you say about the pairs of angles – look at the matching colours.
 
** Once the parallel line reaches the vertex, how many angles are formed?
 
** Once the parallel line reaches the vertex, how many angles are formed?
 
** Students should be able to identify the two angles moving are corresponding angles as the line moving is parallel to one of the sides.
 
** Students should be able to identify the two angles moving are corresponding angles as the line moving is parallel to one of the sides.
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# If a triangle has all three angles are equal in measure, then what will the measure of each angle?
 
# If a triangle has all three angles are equal in measure, then what will the measure of each angle?
 
Go back to the page - [https://karnatakaeducation.org.in/KOER/en/index.php/Triangles?veaction=edit&section=20 click here]
 
Go back to the page - [https://karnatakaeducation.org.in/KOER/en/index.php/Triangles?veaction=edit&section=20 click here]
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[[Category:Triangles]]

Latest revision as of 14:16, 19 December 2020

Objectives

  • To establish the angle sum property of a triangle
  • To help visualization of the geometric proof

Estimated Time

30 minutes

Prerequisites/Instructions, prior preparations, if any

Prior understanding of point, lines and angles, adjacent angles, vertically opposite angles, linear pair, parallel lines, alternate angles, corresponding angles.

Materials/ Resources needed

Click here to open the file

Process (How to do the activity)


Download this geogebra file from this link.


  • Students should be able to recognize the corresponding angles formed when the parallel line is drawn.
  • Students should be able to recognize the alternate angles formed. Is the alternate angle same as one of the angles of the triangle.
    • Ask students what happens when the three angles of the triangle are placed adjacent to each other.
    • What can you say about the line drawn?
    • Is it parallel to one of the sides?
    • What can you say about the pairs of angles – look at the matching colours.
    • Once the parallel line reaches the vertex, how many angles are formed?
    • Students should be able to identify the two angles moving are corresponding angles as the line moving is parallel to one of the sides.
    • Students can see that when the three angles of the triangle are placed adjacent to each other they form a straight line.

Evaluation at the end of the activity

  1. In a triangle, if the sum of two angles is 60°, then what will be the measure of third angle?
  2. If a triangle has all three angles are equal in measure, then what will the measure of each angle?

Go back to the page - click here