How do you find the area of the top and lateral surface of a cylindrical water tank with radius 20 ft and height 30 ft.?

1 Answer
Nov 12, 2016

Answer:

Exact value #->1600pift^2#
Approx value#->5026.5ft^2#

Explanation:

Interesting that the bottom is not required in the solution.

Assumption: The top is not curved but flat.

Let the unit of measurement be #ft# for feet

Area of top #-> pir^2 -> pixx(20ft)^2 ~~1256.6 ft^2 #

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Lateral area #-># height x circumference #->30 ftxxpi D ft#

#=30ftxxpi40ft ~~3769.9ft^2#
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It is more precise to calculate the sum in this way:

#[pi20^2]ft^2+[30xx40pi] ft^2#

#pi(20^2+1200) ft^2#

#1600pift^2 ~~ 5026.5 ft^2#