The volume (in cm³ ) of a right circular cone, whose slant height is 28 cm and radius of base is 21 cm, is (Take π = 22/7 )

Correct option is C

​Given:

Slant height = 28 cm, radius = 21 cm

​$$\pi = \frac{22}{7}$$​​

Formula Used:

$$\text{Height} = \sqrt{\text{Slant height}^2 - \text{Radius}^2}$$ 

$$\text{Volume} = \frac{1}{3} \pi r^2 h$$ 

Solution:

Height: 

$$h = \sqrt{28^2 - 21^2} = \sqrt{784 - 441} = \sqrt{343}$$  

Then volume of the cone = 

$$\text{Volume} = \frac{1}{3} \times \frac{22}{7} \times 21^2 \times \sqrt{343} = 3234\sqrt{7}$$​ cm³