A regular heptagon has seven lines of symmetry. Each one runs from a vertex to the opposite side, bisecting the side at a 90-degree angle.
All regular polygons have as many lines of symmetry as they have sides. For regular polygons with an odd number of sides, the lines of symmetry run from vertex to opposite side, as with the heptagon. For regular polygons with even numbers of sides, the lines of symmetry run alternately from vertex to opposite vertex, and from side to opposite side. In each case, the side is bisected at a 90-degree angle. For a polygon to be considered regular, all of its sides must be of equal length.