An irregular 7 sided heptagon normally has no lines of symmetry depending how it is constructed.
It can have none or one.
None.
Infinite lines of symmetry
2
None.
3
7 be it regular or irregular
It has one line of symmetry
A regular heptagon doesn't have right angles, but an irregular heptagon can have 5 right angles.
A heptagon can have 0, 1 or 7 lines of symmetry. 7 only if it is a regular heptagon.
A heptagon can have all 7 lines that are perpendicular to one or both its neighbours.
A heptagon s bounded by seven straight sides.