>>4179>>4184Decided to take a more interesting approach and see if I can come up with a solution that doesn't involve a concentric circle.
The first shape that comes to mind is, a rectangle inscribed inside the circle but that doesn't seem to be possible. As the rectangle dimensions needed to create equal area portions result in one of the sides being longer than the circles diameter. I used pythagorean theorem to calculate chord length in terms of apothem and radius. The apothem can be rewriten as the rectangle width/2. So I can use this to write the area of the rectangle in terms of chord length and radius. Then by applying the 1/2 circle area constraint from
>>4184 on the rectangle area I could do a bunch of algebra and solve for chord length in terms of radius. I may have messed up my algebra and lost track of roots but I ended up getting length ~= 1.82 * radius. Taking this value and plugging it back into the chord formula to solve for the other side of the rectangle I get width ~= 2.706 * radius. This width value is obviously larger than circle's diameter of 2 * radius.
Seeing as a rectangle doesn't work, I doubt any regular, inscribed, polygon fits the conditions (a triangle probably can).
I wonder if there is any inscribed polygon that can satisfy the OP constraints and do these polygons have to be convex or have to be concave or can they be either (excluding triangles)?