Answer:
10ft
Step-by-step explanation:
I'm not quite sure I understand your question because you seem to have already stated the height of the wall but I found a similar one (see attached).
If the height of the picture is √90 feet. This means it is;
√90 = 9.5 ft
Rounded to the nearest foot is 10 feet.
To be able to hang the painting, the wall would have to be at least 10 ft in height.