Class 7 Maths Chapter 6 Exercise 6.2 Pdf Notes NCERT Solutions
Class 7 Maths Chapter 6 The Triangles And Its Properties Exercise 6.2 pdf notes:-


Exercise 6.2 Class 7 maths Chapter 6 Pdf Notes:-
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Ncert Solution for Class 7 Maths Chapter 6 The Triangles And Its Properties Exercise 6.2 Tips:
ANGLE SUM PROPERTY OF A TRIANGLE
There is a remarkable property connecting the three angles of a triangle. You are going to
see this through the following four activities.
- Draw a triangle. Cut on the three angles. Rearrange them as shown in (i), (ii).
The three angles now constitute one angle. This angle is a straight angle and so has
measure 180°.
Thus, the sum of the measures of the three angles of a triangle is 180°.
- The same fact you can observe in a different way also. Take three copies of any
triangle, say ΔABC
Arrange them as in
What do you observe about ∠1 + ∠2 + ∠3?
(Do you also see the ‘exterior angle
property’?)
- Take a piece of paper and cut out a triangle, say, ΔABC (Fig 6.16).
Make the altitude AM by folding ΔABC such that it passes through A.
Fold now the three corners such that all the three vertices A, B and C touch at M.
You find that all the three angles form together a straight angle. This again shows that
the sum of the measures of the three angles of a triangle is 180°.
- Draw any three triangles, say ΔABC, ΔPQR and ΔXYZ in your notebook.
Use your protractor and measure each of the angles of these triangles.
Tabulate your results
Allowing marginal errors in measurement, you will find that the last column always
gives 180° (or nearly 180°).
When perfect precision is possible, this will also show that the sum of the measures of
the three angles of a triangle is 180°.
You are now ready to give a formal justification of your assertion through logical
argument.