None, since there is no such thing as rational symmetry.
triangle
is a square a rational symmetry? is a square a rational symmetry?
One line of symmetry
none
It has 1 line of symmetry
There are infinitely many lines of symmetry. Every line can be a line of symmetry for a suitable shape.
It has 1 vertical line of symmetry
A line has only 1 line of symmetry that i know of.
Assuming the question is about ROTATIONAL symmetry rather than rational symmetry, the answer is none.
A cardioid has 1 line of symmetry.
A line has 180 degrees rotational symmetry.
The line of symmetry is the reflection of an object. The Letter F does not have a line of symmetry.