You can
put this solution on YOUR website!construct a function expressing the volume V of a cube as as function of the
length of its diagonal d, where d is the line segment joining opposite
non- co- planer vertices of the cube and d is not a side of the cube.
:
drawing this will help:
The hypotenuse they are talking about is formed by the diagonal of the bottom of the cube and the height of the cube
:
Let x = side of the cube
then

= diagonal of the bottom
and
d =

Which is
d =

d =

Solve for x
d^2 = 3x^2

= x^2
which is
x =

:
v = x^3
Substitute

for x:
V(d) =

; is the required function
:
I checked this using x=2, you can do the same