The figure above is a cube. What is the measure of angle BEG

Question

https://gmatclub.com/forum/download/file.php?id=16353 The figure above is a cube. What is the measure of angle BEG (not shown)? A. 30° B. 45° C. 60° D. 75° E. 90° Cube.jpg

Bunuel · Accepted Answer

Note that triangle BEG is equilateral: it's made by the diagonals of the adjacent faces of the given cube (and as faces of a cube are squares its diagonals are equal). Thus angle BEG=60 degrees.

Answer: C.

Bunuel · Answer

Added a question about this issue for a better understating. Cube.jpg The figure above is a cube. What is the measure of angle BEG (not shown)? A. 30° B. 45° C. 60° D. 75° E. 90° Note that triangle BEG is equilateral: it's made by the diagonals of the adjacent faces of the given cube (and as faces of a cube are squares its diagonals are equal). Thus angle BEG=60 degrees. Answer: C. Hope it helps.

htbreme · Answer

Cube - Q.jpg The figure above is a cube. What is the measure of angle BEG (not shown)? A. 30° B. 45° C. 60° D. 75° E. 90° Hi everyone, I wanted to make you a quick and apparently easy question that it's giving me a hard time: What is the angle formed by the diagonals of to perpendicular faces of a cube? I know the answer but I can't visualize why that's the answer Source: local GMAT course Thanks in advance

bicu17 · Answer

Why isn't it 90? Since two diagonals bisect two 90 degree angles would the x angle equal to 90? I understand your explanation, but would like to understand why my thinking is wrong? Thank you.

Bunuel · Answer

It would be correct for 2-D geometry, meaning the angle between two diagonals below is indeed 90 degrees: Squares.png But in 3-D geometry 2 faces are already 90 degrees to each other thus their diagonals would not form 90 degrees any more. Hope it's clear.

gillyelephant · Answer

I don't understand this question. Where is there a triangle/an angle for BEG?

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Bunuel · Answer

https://gmatclub.com/forum/download/file.php?id=16941

Note that triangle BEG is equilateral: it's made by the diagonals of the adjacent faces of the given cube (and as faces of a cube are squares its diagonals are equal). Thus angle BEG=60 degrees.

GMATinsight · Answer

Please find the solution as attached

JeffTargetTestPrep · Answer

Since our given figure is a cube, we must recall that a cube is made up of 6 squares, which of course have all equal sides. We need to determine the measure of angle BEG. Let’s draw that angle in a diagram:

https://i.imgur.com/XMEEtQw.png

From our diagram we can see that we can actually create a triangle using angle BEG with sides BE, EG, and GB. Notice that each side is the diagonal of a square face of the cube and thus is equal in length. Therefore, we know that triangle BEG is an equilateral triangle and furthermore that angle BEG is 60 degrees.

Answer: C

Regor60 · Answer

Easier to visualize if you consider GDB angle so that the telescoped perspective doesn't throw you off.

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bumpbot · Answer

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The figure above is a cube. What is the measure of angle BEG

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The figure above is a cube. What is the measure of angle BEG

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