Question

The exterior diameter of an iron pipe is 25 cm and it is one cm thick. Find the whole surface area of the pipe it is 21cm long

Answer 1

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total surface area is the sum of the inner curved surface area and outer curved surface area of the iron pipe

outer diameter=25cm

outer radius=12.5cm

inner radius=(12.5-1)cm=11.5cm

now the total area is...

$= 2\pi \: (12.5 + 11.5) \times 21 \: \: cm {}^{2} \\ = \frac{2 \times 24\times 21 \times 22}{7} cm {}^{2} \\ = 3168 \: cm {}^{2}$

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