SOLUTION: I have the total surface area, and I have two of the three dimensions given, how do I figure out the missing (third) dimension?

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Question 167320: I have the total surface area, and I have two of the three dimensions given, how do I figure out the missing (third) dimension?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
I have the total surface area, and I have two of the three dimensions given, how do I figure out the missing (third) dimension?
:
Look at the Surface area equation:
Dimensions: L by W by H
;
2LW + 2LH + 2WH = SA
:
Let's say the missing dimension is L. Solve this equation for L
:
Subtract 2WH from both sides:
2LW + 2LH = SA - 2WH
:
Factor out L on the left
L(2W + 2H) = SA - 2WH
:
Divide both side by (2W+2H) and you have:
L = %28%28SA-2WH%29%29%2F%28%282W%2B2H%29%29
;
Substitute the other two dimensions (W & H) and the surface area to find L