sentences:  For the radius of the circle inscribed in the decagram one half of the segment created from the third ray, segment AM, was selected.The following figure illustrates a step-by-step compass-straightedge visual solution to the problem by the author.Note that the way to divide a right angle into five congruent angles is not a part of the instructions provided, because it is considered an elementary step for designers.The girih has been widely applied on the architecture.