Let us think of a cube of butter and cut it, not straight down as a normal human being would, but for some mathematical reason across. We have two wedges.
We are here concerned with the area of the larger face of the wedge, are we not?
The dimensions of this face is 8 by the diagonal of the cube.
The diagonal of the cube acording to Pytagoras (a real friend) is
8 square plus 8 square = 64 + 64 = two 64's under the radical or 8 (square root of 2).
So the area of the face is 8 times 8 (square root of 2) that is 64 times 1.44 some!
(and I do not know how to draw this either.)