1. Let ◇ADCB be the given polygon.
2. Construct a rectangle ◇EFGH such that it has the same area as polygon ◇ADCB.
3. Extend EF to J such that ᅵFJᅵ = ᅵFGᅵ.
4. Bisect EJ at K.
5. Construct the circle through the point J centered at K that intersects the extension of GF at P.
6. Construct a square ◇PFMN with FP as a side. The square ◇PFMN has been constructed equal (in area) to the given polygon ◇ABCD.