Answer:
Approximately 13.1521 units. 
Explanation:
To find the diagonal, we can use the Pythagorean Theorem. 
Since the figure is a square, all four sides are equivalent. A square also has four right angles. Therefore, we can use the Pythagorean Theorem to find the diagonal d. Therefore: 

Substitute 9.3 for a and b, and let c equal d: 

Instead of squaring, add the like-terms:

Take the square root of both sides: 

Expand: 

The right cancels: 
