The length of the diagonal AB of the given square is 8.660
Given that a diagram of a cube having dimensions 5×5×5 and asked to find out the length of diagonal AB(which is a body diagonal of the cube).
To calculate the body diagonal 1st we need to calculate the face diagonal via the Pythagorean theorem
Let's assume the length of the face diagonal is x
By Pythagorean theorem



Therefore, the length of the face diagonal is 
Let's assume the body diagonal is y
By Pythagorean theorem


y=
=8.660
Therefore, The length of the diagonal AB of the given square is 8.660
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