Respuesta :

a cube has all equal sides, so is a square on all faces, however, crossing it diagonally, the left and right sides will be longer, check the picture below.
Ver imagen jdoe0001

Answer:

Triangle

Step-by-step explanation:

A cube is a three-dimensional figure with six congruent square faces. The cube below is sliced by a plane through vertices 1, 6, and 8.

The cross-section created by the plane is an equilateral triangle.

Therefore, triangle  is the best answer.