RD Chapter 20- Surface Areas and Volume of A Right Circular Cone Ex-20.1 |
RD Chapter 20- Surface Areas and Volume of A Right Circular Cone Ex-VSAQS |

Find the volume of a right circular cone with:

(i) radius 6 cm, height 7 cm

(ii) radius 3.5 cm, height 12 cm

(iii) height 21 cm and slant height 28 cm. [NCERT]

**Answer
1** :

(i) Radius of a cone (r) = 6 cm

and height (h) = 7 cm

Find the capacity in litres of a conical vessel with:

(i) radius 7 cm, slant height 25 cm,

(ii) height 12 cm, slant height 13 cm. [NCERT]

**Answer
2** :

(i) Radius of the conical vessel (r) = 7 cm

Slant height (h) = 25 cm

**Answer
3** :
Ratio in the heights of two cones =1:3

and ratio in their radii = 3: 1

Let radius of first cone (r_{1})= x

and of second cone (r_{2})= 3x

and height of first cone (h_{1})= 3y

and of second cone (h_{2})

**Answer
4** :
Ratio in the radius and height of a cone = 5 : 12

Volume = 314 cm^{3}

Let radius (r) = 5x

and height (h) = 12x

**Answer
5** :
Ratio in the radius and height of a right circularcone = 5 : 12

Volume = 2512 cm^{3}

Let radius (r) = 5x

Then height (h) = 12x

**Answer
6** :

Ratio in volumes of two cones = 4:5

and ratio in radii = 2:3

Let radius of the first cone (r_{1}) = 2x

Then radius of second cone (r_{2}) = 3x

Let h_{1}, h_{2} be their heights respectively

**Answer
7** :
Let r be the radius and h be the height of a cylinderand a cone, then

Volume of cylinder = πr^{2}h

**Answer
8** :
Let r be the radius and h be the height of the cone,then

Volume = πr^{2}h

**Answer
9** :
Diameter of conical heap of wheat = 9 m

**Answer
10** :

Diameter of the base of solid cone = 14 cm

and vertical height (h) = 51 cm

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