Your answer would be
You can find this by rearranging the formula
to make s the subject of the formula.
First we can see that this can be written as
Which means we can multiply a by 4 to get:
Then we can divide by √3 :
And finally square root the whole fraction:
So this formula represents the side of an equilateral triangle, with 'a' being the area.
I hope this helps!