Lots of possibilities:
an isosceles triangle,
an isosceles trapezium,
an irregular polygon with an odd number of sides, where the sides and angles on either side of the base are symmetric.
An isosceles triangle and a kite have only one line of symmetry.
septahedron
A 2d shape with uncountable lines of symmetry is a circle.
Octagon
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The 2D shape which has one line of symmetry is the trapezium.
An isosceles triangle and a kite have only one line of symmetry.
A square
Square
Ss
A triangle, an oval, a trapezoid as well I think.
Septahedron
septahedron
1
A 2d shape with uncountable lines of symmetry is a circle.
Octagon
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