The perimeter of the ends of a frustum of a cone are 44 cm and 8.4 π

1.	The perimeter of the ends of a frustum of a cone are 44 cm and 8.4 π cm. If the depthis 14 cm., then find its volume.
Answer» Given, Perimeter, P1= 2πr1= 44 cm Then, r1=44/2π=22×7/22= 7 cm Perimeter, P2= 2πr2= 8.4π cm Then, r2=8.4π/2π= 4.2 cm Given: h = 14 cm Volume =1/3πh(r12+ r22+ r1r2) =1/3x π x 14 [(7)2+ (4.2)2+ (7 x 4.2)] =1/3x22/7x 14(49 + 17.64 + 29.4) = 1408.58 cm3

The perimeter of the ends of a frustum of a cone are 44 cm and 8.4 π cm. If the depthis 14 cm., then find its volume.

Answer»

Given, Perimeter, P1= 2πr1= 44 cm

Then, r1=44/2π=22×7/22= 7 cm

Perimeter, P2= 2πr2= 8.4π cm

Then, r2=8.4π/2π= 4.2 cm

Given: h = 14 cm

Volume =1/3πh(r12+ r22+ r1r2)

=1/3x π x 14 [(7)2+ (4.2)2+ (7 x 4.2)]

=1/3x22/7x 14(49 + 17.64 + 29.4)

= 1408.58 cm3