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

Algebra ->  Triangles -> 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      Log On


   



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) About Me  (Show Source):
You can put this solution on YOUR website!
The green triangle is an equilateral triangle.
Its sides measure 3%2A%286cm%29=18cm .
The height of an equilateral triangle is side%2Asin%2860%5Eo%29=side%2A%28sqrt%283%29%2F2%29 .
The height of the green triangle is
%2818cm%29%2A%28sqrt%283%29%2F2%29=9sqrt%283%29cm .
THe radius of the pipes is 6cm%2F2=3cm 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
3cm%2B9sqrt%283%29cm%2B3cm=highlight%286%2B9sqrt%283%29%29cm