Area of community fitness facilities

The area of quadrilateral ABCD is 200m2, and AB = 20m.

Then AD= 10 meter,

In rt delta ADe, ad is the hypotenuse,

It is known that AD = 10m, AE = 8m,

So DE =AD2? Ae2 = 6m,

Therefore, the diameter of the semicircular dining area is 6 meters.