A regular decagon is made up of ten sides and ten vertices. Each vertex is located exactly in front of another vertex (opposite). Then, by drawing axes that join two opposite vertices, five axes of symmetry can be constructed.
Each side is located exactly opposite the other side of the decagon (opposite). Then, joining the midpoints of each side, with their respective opposite, five axes of symmetry are constructed for the decagon.
Conclusion: the regular decagon has 10 axes of symmetry.
