A polygon.
A triangle as no other 2d shape can have 3 sides.
A cube is a 3 dimensional shape but it can be represented by a 2D net
A triangle
a cuboid is a 3 dimensional shape
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
A polygon.
A triangle as no other 2d shape can have 3 sides.
A cube is a 3 dimensional shape but it can be represented by a 2D net
A 3 dimensional triangle is called a pyramid, otherwise a 2D three sided polygon shape is exactly what you called it, a triangle.
a triangle
A triangle
a cuboid is a 3 dimensional shape
One answer is triangle
It is a 3 dimensional shape
An acute angled triangle
Definately a triangle