Question

An iron pipe 20 cm long has exterior diameter equal to 25 cm.if the thickness of the pipe is 1 cm,find the whole surface area of the pipe.

Answer 1

Hey there !!
Thank u for ur question
Let R , r , and h be the External radius , internal radius , and height respectively

Given that -
R = 25/2. = 12.5 cm

Internal diameter , D = 25-2 =23

r = 23/2 = 11.5

Total surface area of the pipe =

$2\pi \: h(r1 + r2) + 2\pi( {r1}^{2} - {r2}^{2}) \\ = > 2 \times \frac{22}{7} \times 20(12.5 + 11.5) + 2 \times \frac{22}{7} (( {12.5)}^{2} - ( {11.5}^{2} ) \\ = > \frac{44 \times 480}{7} + \frac{1056}{7} \\ = > \frac{22176}{7} \\ = > 3158 {cm}^{2}$
Hope this helps u !!
AK02
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