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A circular hole of diameter 2 cm is drilled from the center of the top to the bottom.

a) Find the volume of the new solid. Give the answer to the nearest cubic unit.
b) Find the area of the inner surface of the new solid to the nearest square unit.



By the way, all these are in centimeter units.

 Feb 1, 2021
 #1
avatar+116126 
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a)  Volume of the  new solid =   

 

Volume of original cylinder  - volume of  drilled out  cylinder  =

 

pi  * 6  (  3.5^2   -  2^2)    =    49.5 pi  cm^3 ≈  156 cm^3

 

 

b)  Area of  inner  surface  =  lateral surface area of   drilled out part = 

 

2 * pi  *  r  *  h   = 

 

2 * pi *  2  *  6   =      24 pi  cm^2   ≈  75 cm^2

 

 

cool cool cool

 Feb 1, 2021

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