Calculate the amount of area you have to work with
Since a Box has all equal sides(or faces) and this will be an open box calculate the number of sides
Use this information versus the area you have to work with.
12 inches by 18 inches
12 x 18 = 216 square inches of card board area to work with
If you want one large opened top box with a total surface area of 216 square inches
The surface area of box is 6s2 because all the sides are equal on each face.
But you need an opened box so the surface area will be 5s2 because there is no top (6s2 - 1s2)
You could try the following:
216 = 5s2
Divide both sides by 5
43.2 = s2
Get the square root of 43.2 to find s
√43.2 = s
6.572 = s
You can check by keeping in mind that your box has one bottom, four sides, and NO TOP so the surface area is for one large box.
5*(6.572)2 = 5*43.19 = 215.95 square inches
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