There is no such word as a "hepticgon". A heptagon can have 0, 1 or 7 lines of symmetry.
A nephroid has 2 lines of symmetry.
it has five lines of symmetry
10 lines of symmetry
4 Lines of symmetry
2 lines OF SYMMETRY
2 lines of symmetry
It has 2 lines of symmetry.
no lines of symmetry
2 lines of symmetry
5 lines
There is no such thing as 8 lines of symmetry. A circle, for example, has infinitely many lines of symmetry.
There are infinitely many lines of symmetry. Every line can be a line of symmetry for a suitable shape.