Question

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

Answer 1

GIVEN: height of pipe = 20cm

exterior diameter of pipe = 25cm

thickness of pipe = 1cm

TO FIND: total surface area of pipe

FORMULA: 2πr(r+h)

SOLUTION:pipe is cylindrical

diameter = 2 x radius

radius = 12.5

∴total surface area of cylinder = 2πr(r+h)

= 2 x $\frac{22}{7}$ x 12.5 ( 12.5 + 20)

=  2 x  $\frac{22}{7}$ x 12.5 x 32.5

= 2 x  $\frac{22}{7}$ x 406.25

= 812.5 x 3.14

=2551.25 cm^2

total surface area of cylinder = 2πr(r+h)

= 2 x $\frac{22}{7}$ x 11.5 ( 11.5 + 20)

=2 x  $\frac{22}{7}$ x 12.5 x 31.5

= 2 x  $\frac{22}{7}$ x 393.75

= 787.5 x 3.14

=2472.75 cm^2

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