Chapter 6 grsde 7 The Triangle and its Properties.pptx

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1. Contents 1. Triangle 2. Types of Triangles 3. Medians and Altitudes of a Triangle 4. Exterior angle in a Triangle 5. Inequalities in a Triangle 6. Angle sum property in a Triangle 7. Pythagoras Theorem 8. Summary 9. Practice Paper

2. TYPES OF TRIANGLES ON THE BASIS OF ANGLES

3. Every triangle has exactly three medians, one from each vertex, and they all intersect each other at the triangle's centroid.

4. THINK ABOUT IT AND WRITE 1. Does a median lie wholly in the interior of the triangle? 2. Will an altitude always lie in the interior of a triangle? 3. Can the altitude and median be same for a triangle?

5. The sum of the interior angles of a triangle is always equal to 180°.

6. THINK ABOUT IT AND WRITE 1. What can you say about each of the interior opposite angles, when the exterior angle is (i) a right angle? (ii) an obtuse angle? (iii) an acute angle? 2. Can you have a triangle with two acute angles? 3. Can you have a triangle with all the three angles greater than 60º?

7. A right triangle consists of two sides called the legs and one side called the hypotenuse. The hypotenuse is the longest side and is opposite the right angle.

8. Pythagorean Theorem : In any right triangle, the sum of the squared lengths of the two legs is equal to the squared length of the hypotenuse .

9. Summary of This Chapter

10. Practice Paper Q.1) How many medians a triangle can have? Q.2) A _____________ connect a vertex of a triangle to the mid-point of the opposite side. Q.3) How many altitude can a triangle have? Q.4) A triangle in which two sides are of equal length is called _______________ triangle. Q.5) The sum of the lengths of any two sides of a triangle is _____________ the third side of the triangle.

11. Q.6) PQR is a triangle, right-angled at P. If PQ = 10 cm and PR = 24 cm, find QR. Q.7) Is it possible to have a triangle with the following sides? (i) 2 cm, 3 cm, 5 cm (ii) 3 cm, 6 cm, 7 cm Q.8) Can you have a triangle with all the three angles equal to 60º? If have then write name.