A 2D shape with 9 sides is called a Nonagon.
A '2d' ( 2-dimensional) shapoe is a straight line, or a polygon.
A pentagon
Hexagon
Octagon
The 2D equivalent of a sphere is a circle so it follows that the 2D equivalent of a hemisphere is a semicircle.
A hemisphere is a three dimensional shape that is essentially the same as half of a sphere.
A semi-circle.
A 2D shape with 9 sides is called a Nonagon.
Octagon
2D shapes include squares, triangles, rectangles and circles.
A '2d' ( 2-dimensional) shapoe is a straight line, or a polygon.
Square
Tetradecagon.
A pentagon
Hexagon
Octagon