Angles in a Cube I

Let denote the vertices of a cube ABCD (for the bottom face) and A'B'C'D' (for the top face), with A' above A, etc. What is the angle AB'C?


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Solution

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Solution

Add to the picture the side AC. As all three segments AB', B'C and AC are the diagonals of equal squares, they are equal and, thus, form an equalteral triangle, implying that angle AB'C is 60°.


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Related material
Read more...

  • Angles in a Cube II
  • Angles in a Cube III
  • Bimedians in a Regular Tetrahedron
  • Cut the Cone
  • Cut the Cube
  • Cut the Cylinder
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