A semicircle.
The 2D equivalent of a sphere is a circle so it follows that the 2D equivalent of a hemisphere is a semicircle.
The answer might depend on what the first nine are. Is a circle already counted? A semicircle, a quadrant, an ellipse, and so on. And if not, why not?
A semicircle is a two-dimensional shape that is half of a circle, with a flat edge as the diameter. A hemisphere, on the other hand, is a three-dimensional shape that is half of a sphere, with a curved surface. Essentially, a semicircle lies in a plane, while a hemisphere is a solid object.
Semicircle
It's a 2D shape.
A rhombus is a 2D shape.
2d
this is the shape of 2d cone
10 sided 2D shape is called a decagon 20 sided 2D shape is called a icosagon 30 sided 2D shape is a swimming pool 40 sided 2D shape is unknown 50 sided 2D shape is unknown 60 sided 2d shape is unknown 70 sided 2d shape is unknown 80 sided 2d shape is unknown 90 sided 2d shape is unknown 100 sided 2d shape is unknown 110 sided 2d shape is unknown 111 sided 2d shape is unknown 120 sided 2d shape is unknown 130 sided 2d shape is unknown
2d
it a triangle as a 2d shape