BekahXD
contestada

Please can you help me with my question! I'm desperate! It's due for Monday:

Is it possible to remove ten unit cubes from a 3 by 3 by 3 cube made from 27 unit cubes so that the surface area of the remaining solid is the same as the surface area of the original 3 by 3 by 3 cube? In how many different ways can this be done?

Thank you! I'd really appreciate if you could help! Xx

Respuesta :

I observed that if I remove one (or all 8) piece(s) in the corners, and only them without adjacent ones, the total area does not change.

I consider the surface area of a small square as a unit of surface.

First class of solutions:

I removed all eight corners, leaving the total area unchanged.

I removed the central cube of the top surface obtaining an increase of the surface area with four units.

I removed one cube from the middle of an edge at the top (any of the four remaining) and I arrived at a figure with ten cubes less then the original one but with the same surface area.

(There's a lot more solutions here: https://nrich.maths.org/787/solution)