When dealing with polygons, an "extended side" is the line that contains one of the polygon's sides.
So we take a finite line segment (the side of the polygon) and imagine it stretching infinitely in both directions.
When dealing with polygons, an "extended side" is the line that contains one of the polygon's sides.
So we take a finite line segment (the side of the polygon) and imagine it stretching infinitely in both directions.