Class 7 Maths Chapter 6 The Triangles And Its Properties Exercise 6.3 pdf notes:-
Exercise 6.3 Class 7 maths Chapter 6 Pdf Notes:-
Ncert Solution for Class 7 Maths Chapter 6 The Triangles And Its Properties Exercise 6.3 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.
The three angles now constitute one angle. This angle is a straight angle and so has
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 ∆ABC
- Take a piece of paper and cut out a triangle, say, ∆ABC.Make the altitude AM by folding ∆ABC 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 thatthe sum of the measures of the three angles of a triangle is 180°.
- Draw any three triangles, say ∆ABC, ∆PQR and ∆XYZ in your notebook.Use your protractor and measure each of the angles of these triangles.Tabulate your resultsName of ∆ Measures of Angles Sum of the Measuresof the three Angles∆ABC m∠A = m∠B = m∠C = m∠A + m∠B + m∠C =∆PQR m∠P = m∠Q = m∠R = m∠P + m∠Q + m∠R =∆XYZ m∠X = m∠Y = m∠Z = m∠X + m∠Y + m∠Z =Allowing marginal errors in measurement, you will find that the last column alwaysgives 180° (or nearly 180°).When perfect precision is possible, this will also show that the sum of the measures ofthe three angles of a triangle is 180°.You are now ready to give a formal justification of your assertion through logicalargument.Statement The total measure ofthe three angles of atriangle is 180°.To justify this let us use the exteriorangle property of a triangle.