htbreme wrote:

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

Added a question about this issue for a better understating.

Attachment:

The attachment **Cube.jpg** is no longer available

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.

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.