Recent content by mary.neola

  1. M

    Angle between two diagonals of a cube.

    Find the angle between the diagonals of the back and left faces of a cube with one vertex on the origin. A) 60 degrees B) arcos(1/sqrt(6)) C) arcos(1/(3sqrt(2)) D) 90 degrees E) 120 degrees. I think the answer should be D) 90 degrees. Since these vectors are diagonals on the face of the cube...