( Rs 2068)13. A right circular cone is 3.6cm high and radius of its ba

1.	( Rs 2068)13. A right circular cone is 3.6cm high and radius of its base is 1.6cm. It is melted and recast into a ricircular cone with radius of its base as 1.2cm. Find its height.(6.4 cm)
Answer» For cone, h = 3.6 cm, r = 1.6 cm Volume of the given cone = 1/3 x Π2h = (1/3 x 22/7 x 1.6 x .16 x 3.6) cm2 Radius of the second cone = 1.2 cm. Let its height be h1</sup> then, Volume of the second cone = 1/3 x Π r2h = 1/3 x 22/7 x 1.2 x h1 it is melted and recasted so ,the volume of the cones would be equal, therefore 1/3 x 22/7 x 1.2 x h1= 1/3 x 22/7 x 1.6 x .16 x 3.6 h1= (1.6 x 1.6 x 1.6) / (1.2 x 1.2) = 6.4 Hence the height of the second cone is 6.4 cm

( Rs 2068)13. A right circular cone is 3.6cm high and radius of its base is 1.6cm. It is melted and recast into a ricircular cone with radius of its base as 1.2cm. Find its height.(6.4 cm)

Answer»

For cone, h = 3.6 cm, r = 1.6 cm

Volume of the given cone = 1/3 x Π2h = (1/3 x 22/7 x 1.6 x .16 x 3.6) cm2

Radius of the second cone = 1.2 cm. Let its height be h1</sup> then,

Volume of the second cone = 1/3 x Π r2h = 1/3 x 22/7 x 1.2 x h1

it is melted and recasted so ,the volume of the cones would be equal, therefore

1/3 x 22/7 x 1.2 x h1= 1/3 x 22/7 x 1.6 x .16 x 3.6

h1= (1.6 x 1.6 x 1.6) / (1.2 x 1.2) = 6.4

Hence the height of the second cone is 6.4 cm