Answer:
4
Explanation:
due to the fact that this shape is a rhombus the point of intersection between two diagonals is perpendicular to each other.
Then notice that the sections are right triangles and x is the hypotenuse
using Pythagorean theorem
A*2+B*2=C*2
3*2+5*2=x*2
9+25=x*2
34=x*2
x=√34