The line (or surface) across which things are (exactly) the same.
Look in a mirror. Draw a line from your head to between your feet. You are considered symmetrical to your left/right ... but not up/down nor front/back.
The question should have been written as "What are axes of symmetry?" because axes is plural and axis is singular.
There are infinitely many axes of symmetry in mathematics.
A regular pentagon has five axes of symmetry.
2 axes from angles to angles
4
one
A rectangle has 2 axes of symmetry.
a rectangle has 2 axes of symmetry
There are infinitely many axes of symmetry in mathematics.
It has 5 axes of symmetry
A square has 4 axes of symmetry.
A regular pentagon has five axes of symmetry.
An isosceles triangle definitely has three axes of symmetry
A polygon need not have any axes of symmetry. It can have at most n axes where n is the number of sides that the polygon has.
Not sure about a duodecagon, but a regular dodecagon has 12 axes of symmetry.
perpendicular through any vertex. so there are three axes of symmetry.
10 axes of symmetry
2 axes from angles to angles