The total surface area of a cylinder is 616 cm square if the ratio of surface area and total surface area is 1 is to 2 find the volume of the cylinder
Answers
We have curved surface area= 2π*r*h
we have the circular surface area= 2πr²
ATQ 2πr(h+r)= 616 ---(1)
and 2*2πrh= 2πrh+ 2πr²
⇒ h=r
Substituting value of h in (1)
we have 4πr²=616
⇒ r²=59
⇒ r=7
Volume of the cylinder is
⇒ πr².h= πr³
⇒ = πr³=1078cm³
Answer:
given csa:tsa =1:2
therefore tsa = 2×csa
tsa = 616 cm²
TSA = 2πr (h + r)
CSA = 2πrh
csa:tsa = 1:2
2πrh : 2πr(h+r) = 1:2
(2πrh)/(2πr(h+r) = 1/2
(h) /(h+r) = 1/2 [on cancelling 2πr on both num. and den.]
2h = h+r
2h-h = r
h = r
so height and the radius are equal
tsa = 616cm²
2πr(h+r)=616cm²
2πr(r+r) = 616 [as h=r]
2πr(2r) = 616
4πr² = 616
πr² = 616/4
r² = 154/π
r² = 49
r = 7
hence r=h=7cm
volume of cylinder = πr²h
= π7²×7 = π7³
= 22/7 × 7³
= 22×7²
=1078cm³