[ª] , [©] , [^] , [¨]Bisectors of four corners of quadrangle / In the condition of particular shape(GC World : Various Problems ,Quadrangle¨Quadrangle)
What rules exist in this figure?
Let's change this shape into general quadrangle.
What is the limit of availability of rule which you found?

GC/Win


Forum of Geometric Constructor by Y.Iijima