[Math] find width of path

geometry

suppose we have following question

A square garden is surrounded by a path of uniform width. If the path and the garden both have an area of $x$, then what is the width of the path in terms of $x$?

so we have following picture right

enter image description here

because we dont know if path of uniform width is square or not how can i find width?if area of square is $x$,then length is $\sqrt{x}$,but what about second figure?suppose it's length are $a$ and $b$,then $a*b=x$,then how can i continue?

Best Answer

You would have

$$4 w \sqrt{x} + 4 w^2 = x$$

(i.e., four rectangles + four squares that make up path, width of path = $w$)

Solve for $w$:

$$2 w = \frac{-\sqrt{x} \pm \sqrt{2 x}}{2}$$

Choose the positive solution:

$$w=\frac{\sqrt{2}-1}{4} \sqrt{x}$$

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