In geometry, the only shape that has one surface is a plane.
A sphere has only one surface.
a sphere
Circle
A hemisphere
hemisphere
A cardioid is one possibility. See link, below.
a sphere
Both. ANY 2-dimensional shape ... that is, a shape drawn in a plane, or on a piece of paper ... has only one surface.
Sphere
a sphere
The shape with just one surface is.... a sphere.
A sphere
A trapezium is a plane shape and so has only one surface.
sphere
A 2D shape is flat and only has a surface area whereas a 3D shape is an object that has surface area and volume.
a cone.
A sphere
a sphere