Class 6 - Mathematics : Understanding Elementary
Exercise : 5.6
Top Block 1
NCERT Solutions Class 6 Mathematics Understanding Elementary Ex 5.6
Question: 1.Name the types of following triangles:
(a)Triangle with lengths of sides 7 cm, 8 cm and 9 cm.
(b)δABC with AB = 8.7 cm, AC = 7 cm and BC = 6 cm.
(c)δPQR such that PQ = QR = PR = 5 cm.
(d)δDEF with m∠D = 90°
(e)δXYZ with m∠Y = 90° and XY = YZ
(f)δLMN with m∠L = 30°,m∠M = 70° and m∠N = 80°.
Answer :
(a) Scalene triangle
(b) Scalene triangle
(c) Equilateral triangle
(d) Right-angled triangle
(e) Isosceles right-angled triangle
(f) Acute-angled triangle
Question: 2.Match the following:
Measure of Triangle Types of Triangle
| Column A | Column B |
|---|---|
| 1. 3 sides of equal length | A. Scalene |
| 2. 2 sides of equal length | B. Isosceles right angle |
| 3. All sides are of different length | C. Obtuse angle |
| 4. 3 acute angles | D. Right angle |
| 5. 1 right angle | E. Equilateral |
| 6. 1 obtuse angle | F. Acute angle |
| 7. 1 right angle with two sides of equal length | G. Isosceles |
Answer :
| Column A | Column B |
|---|---|
| 1. 3 sides of equal length | E. Equilateral |
| 2. 2 sides of equal length | G. Isosceles |
| 3. All sides are of different length | A. Scalene |
| 4. 3 acute angles | F. Acute angle |
| 5. 1 right angle | D. Right angle |
| 6. 1 obtuse angle | C. Obtuse angle |
| 7. 1 right angle with two sides of equal length | B. Isosceles right angle |
Question: 3.Name each of the following triangles in two different ways: (You may judge the nature of angle by observation)
Answer :
(a) Acute angled triangle and Isosceles triangle
(b) Right-angled triangle and Scalene triangle
(c) Obtuse-angled triangle and Isosceles triangle
(d) Right-angled triangle and Isosceles triangle
(e) Equilateral triangle and acute angled triangle
(f) Obtuse-angled triangle and scalene triangle
Question: 4.Try to construct triangles using match sticks. Some are shown here.
Mddle block 1
(a)3 matchsticks?
(b)4 matchsticks?
(c)5 matchsticks?
(d)6 matchsticks?
(Remember you have to use all the available matchsticks in each case)
If you cannot make a triangle, think of reasons for it.
Answer :
(a) 3 matchsticks
This is an acute angle triangle and it is possible with 3 matchsticks to make a triangle because sum of two sides is greater than third side.
This is a square, hence with four matchsticks we cannot make triangle.
This is an acute angle triangle and it is possible to make triangle with five matchsticks, in this case sum of two sides is greater than third side.
This is an acute angle triangle and it is possible to make a triangle with the help of 6 matchsticks because sum of two sides is greater than third side.
