Bunuel
What is the volume of the smallest cube that is needed to enclose a cuboid of dimensions 10 cm × 5 cm × 2 cm, such that the cuboid can be placed inside the cube in any possible orientation?
(A) 100 cm^3
(B) (125)^(3/2) cm^3
(C) (129)^(3/2) cm^3
(D) (100)^(3/2) cm^3
(E) (139)^(3/2) cm^3
It will become much easy if we consider this cuboid to be a sphere and then adjust this sphere/ball in cube. 1) Cuboid into a sphereThe diameter of this sphere should be equal to the largest possible diagonal of the cuboid, so that the cuboid can rotate inside this sphere without any obstruction.
Largest diagonal = \(\sqrt{10^2+5^2+2^2}=\sqrt{129}\)
2) Sphere into a cubeIf each side of the cube is equal to the diameter of the sphere, the sphere can roll inside the cube.
So side of cube = \(\sqrt{129}\)
Volume of the cube = \((\sqrt{129}^3\)
C
Of course the side may have to be just slightly more to ensure smooth roll of the cuboid inside, but will not effect the volume/side in any significant manner.