SOLUTION: a pile of water pipes is stacked with 4 along bottom, then 3, the 2 then 1. (from the side it looks like a pyramid) If the diameter of each pipe is 6 cm, then the height of the st

Question 833495: a pile of water pipes is stacked with 4 along bottom, then 3, the 2 then 1. (from the side it looks like a pyramid) If the diameter of each pipe is 6 cm, then the height of the stack, in cm, is:
a)6+18 sqrt3
b) 9 sqrt3
c) 15
d) 12+9 sqrt3
e) 6+ 9 sqrt 3
Answer by KMST(5328) (Show Source): You can put this solution on YOUR website!
The green triangle is an equilateral triangle.
Its sides measure .
The height of an equilateral triangle is .
The height of the green triangle is
.
THe radius of the pipes is and the pile's height includes:
a radius of the pipes in the bottom row (below the green triangle), plus
a radius of the top pipe (above the green triangle).
So the total height is

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