Twice as many sides means there must be an even number of sides less than 8. That leaves 6, 4 or 2 sides. Can't be 2 sides; that's not a polygon. If it has 4 sides (and that's twice the number of sides), that would mean the original polygon would have 2 sides. Not a polygon as stated before. Must be six sides (hexagon) and the original would have 3 sides (triangle).