RD SHARMA Solutions for Class 9 Maths Chapter 11 - Triangle and its Angles
Chapter 11 - Triangle and its Angles Exercise Ex. 11.1
Solution 1
Solution 2
Solution 3
Solution 4
Solution 5
Solution 6
(i) No
As two right angles would sum up to 180o, and we know that the sum of all three angles of a triangle is 180o, so the third angle will become zero. This is not possible, so a triangle cannot have two right angles.
(ii) No
A triangle cannot have 2 obtuse angles, since then the sum of those two angles will be greater than 180o which is not possible as the sum of all three angles of a triangle is 180o.
(iii) Yes
A triangle can have 2 acute angles.
(iv) No
The sum of all the internal angles of a triangle is 180o. Having all angles more than 60o will make that sum more than 180o, which is impossible.
(v) No
The sum of all the internal angles of a triangle is 180o. Having all angles less than 60o will make that sum less than 180o, which is impossible.
(vi) Yes
The sum of all the internal angles of a triangle is 180o. So, a triangle can have all angles as 60o. Such triangles are called equilateral triangles.
Solution 7
Solution 8
Solution 9
Solution 10
Solution 11
Solution 12
Chapter 11 - Triangle and its Angles Exercise Ex. 11.2
Solution 1
Solution 2
Solution 3(i)
Solution 3(ii)
Solution 3(iii)
Solution 4
Solution 5
Solution 6
Solution 7
(i) 180o
(ii) interior
(iii) greater
(iv) one
(v) one
Solution 8
Solution 9
Solution 10
Solution 11
Solution 12
Solution 13
Solution 14
Solution 15
Chapter 11 - Triangle and its Angles Exercise 11.25
Solution 1
Let the measure of each angle be x°.
Now, the sum of all angles of any triangle is 180°.
Thus, x° + x° + x° = 180°
i.e. 3x° = 180°
i.e. x° = 60°
Hence, correct option is (c).
Solution 2
Let the measure of each acute angle of a triangle be x°.
Then, we have
x° + x° + 90° = 180°
i.e. 2x° = 90°
i.e. x° = 45°
Hence, correct option is (b).
Solution 3
Solution 4
Let the three angles of a triangle be A, B and C.
Now, A + B + C = 180°
If A = B + C
Then A + (A) = 180°
i.e. 2A = 180°
i.e. A = 90°
Since, one of the angle is 90°, the triangle is a Right triangle.
Hence, correct option is (d).
Solution 5
Solution 6
Solution 7
Solution 8
Solution 9
Solution 10
Solution 11
Solution 12
Chapter 11 - Triangle and its Angles Exercise 11.26
Solution 13
Solution 14
Solution 15
Solution 16
Chapter 11 - Triangle and its Angles Exercise 11.27
Solution 17
Solution 18
Solution 19
Solution 20
Chapter 11 - Triangle and its Angles Exercise 11.28
Solution 21
Solution 22
Solution 23
Solution 24
Chapter 11 - Triangle and its Angles Exercise 11.29
Solution 25
Solution 26
Solution 27
Solution 28
Solution 29
Solution 30
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