# If the triangle ABC in the Question 7 above is revolved about the side 5 cm, then find the volume of the solid so obtained. Find also the ratio of the volumes of the two solids obtained in Questions 7 and 8

**Solution:**

Since the triangle is revolved about the side 5 cm, a solid cone if formed with a height of 5 cm and radius of the base of 12 cm.

Volume of a cone having radius 'r' and height 'h' = 1/3πr²h

Radius of the cone, r =12cm

Height of the cone, h = 5cm

Volume of the cone = 1/3πr²h

= (1/3) × π × 12cm × 12cm × 5cm

= 240π cm³

Volume of the cone in question 7 = 100π cm

Ratio = Volume of the cone in question 7 : Volume of the cone in question 8

= 100π : 240π

= 5 :12

The volume of the cone is 240π cm³ and the required ratio is 5 :12

**Video Solution:**

## If the triangle ABC in the Question 7 above is revolved about the side 5 cm, then find the volume of the solid so obtained. Find also the ratio of the volumes of the two solids obtained in Questions 7 and 8.

### NCERT Solutions for Class 9 Maths - Chapter 13 Exercise 13.7 Question 8:

**Summary:**

It is given that the triangle ABC in the question above is revolved about the side 5 cm. We have found that the volume of the cone is 240π cm³ and the required ratio is 5 : 12.