Question

A metal pipe is 82 cm long .The inner diameter is 12cm and outer diameter is 16cm find its total surface area .

Answer 1

lateral surface area of a cylinder=2πrh
inner diameter=12cm
outer diameter=16cm
total surface area = area of two lateral surface area+ area of 2rings
=(2×22/7×12×82)+(2×22/7×16×82)+{2(22/7×16×16)-(22/7×12×12)}
[22/7×2×82(12+16)+{2(22/7(16×16-12×12)}]
{(22/7×2×82×28)+(2×22/7×112)}
{(22×2×82×4)+(22×2×16)}
{22×2(82×4+16)}
44×344
=15136 cm^2