Question 717718
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: {{{s^2}}}. The area of all six square faces will be: {{{6s^2}}}. We are told that the total surface area is 864 square inches. So:
{{{6s^2 = 864}}}
Now we solve for s. Dividing by 6:
{{{s^2 = 144}}}
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.:
{{{s = 12}}}
So the length of one edge of the cube is 12 inches.