Regions between Circles and Squares
A common application of the area of a circle and the area of a square are problems where a circle is circumscribed about a square or inscribed in a square. Regions between circles and squares problems almost always involve subtracting the two areas; their difficulty stems from dimensions given for one but not both shapes.

Area of shaded region = A_{square}  A_{circle}
Area of shaded region =
Area of shaded region = 
If all circles are tangent to each other and the square, find the shaded area.