Answer:
7.1 cm
Step-by-step explanation:
The diagonal of a cube connects two opposite corners.
You can use the diagonal of a cube in a right triangle in which it is the hypotenuse. The legs of the triangle are a diagonal of a face and an edge.
Let the length of the edge be s.
a^2 + b^2 = c^2
s = 7.1
Answer: 7.1 cm