Question 714783
  1- a metalic pipe is .7cm thick inner radius of the pipe is 3.5cm and length is 5dm find its total surface area
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The length is 50 cm
The inner radius is 3.5 cm
{{{Area = 2*pi*r*h = 2*pi*3.5*50}}}
= 350pi sq cm
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The outer radius is 4.2 cm
{{{Area = 2*pi*r*h = 2*pi*4.2*50}}}
= 420pi sq cm
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The area of each end is {{{pi*(4.2^2 - 3.5^2) = 5.39pi}}} sq cm
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Total area = 780.78*pi sq cm