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 180Ā°.

Thus, the sum of the measures of the three angles of a triangle is 180Ā°.

- The same fact you can observe in a different way also. Take three copies of any

triangle, say ĪABC

Arrange them as in

What do you observe about ā 1 + ā 2 + ā 3?

(Do you also see the āexterior angle

propertyā?)

- Take a piece of paper and cut out a triangle, say, ĪABC (Fig 6.16).

Make the altitude AM by folding ĪABC 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 180Ā°.

- Draw any three triangles, say ĪABC, ĪPQR and ĪXYZ 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 180Ā° (or nearly 180Ā°).

When perfect precision is possible, this will also show that the sum of the measures of

the three angles of a triangle is 180Ā°.

You are now ready to give a formal justification of your assertion through logical

argument.