Question

48.The radius and height of a cylinder are in the ratio 3:7 and its volume is 101376 cubic cm. Find its total surface area.

Answer 1

let proportiobality constant =x
radius =3x
height =7x
now,
volume of cylinder=pi. (3x)^2. (7x)=pi. (63) x^3=101376 cm^3
x=8
radius =24 cm
height=56 cm
total surface area=2pi.r (r+h)=2 x 22/7 x 24 x 70 = 44 x 240= 10560 cm^2

Answer 2

Assume that the radius and height of the cylinder are 3x and 7x respectively.
Volume = π r ²h = 101376 cm³
V = 22/7 × (3x)² × 7x = 101376 cm³
22/7 ×  9 x² × 7x = 101376 cm ³
22/7 × 63 x³ = 101376 cm ³
63 x³ = 101376 × 7/22
63 x³ = 32256
x³ = 32256 ÷ 63
x³ = 512
x= ∛512
x = 8 cm

Radius , r = 3 x = 3 × 8 = 24 cm
Height , h = 7 x = 7 × 8 = 56 cm

T.S.A of cone =  2πr(r+h)
                      = 2 × 22/7 × 24×(24+56)
                      = 2 × 22/7 × 24 × 80
                      = 12068.5714 cm²
-------------------------------------------------------------------------------------------------------------------------------------------------------------------

Please mark brainliest ...