SOLUTION: determine the length of one edge of a cube that has a surface area of 864 square inches

Question 717718: determine the length of one edge of a cube that has a surface area of 864 square inches
Answer by jsmallt9(3758) (Show Source): You can put this solution on YOUR website!
The surfaces/faces of a cube are squares. There are six identical square faces on a cube. The "length of one edge of the cube" will be the length of a side of one of the square faces. If we call the length of the side of a square "s", then the area of one square face will be: . The area of all six square faces will be: . We are told that the total surface area is 864 square inches. So:

Now we solve for s. Dividing by 6:

Find the square root of each side. When finding the square root of each side you should either remember the negative square root or have a specific reason for ignoring it! Since s is the a length and lengths aren't negative, we can ignore the negative square root.:

So the length of one edge of the cube is 12 inches.
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