A cube has all the sides equal.
A diagonal then acts as the hypotenuse of a face such that,
Sin 45° = Side/hypotenuse = Side/12.8 => Side = Hypotenuse * Sin 45 = 9.05 in
Volume = base*width*height = sides^3 (since all sides are equal) = 9.05^3 =741.22 in^3
To nearest tenth,
Volume = 741.2 in^3 {and correct answer is A)}
