A 2D shape becomes 3D by the addition of a third dimension: depth (or thickness or height).
In essence, a 2D shape exists only on a flat plane, defined by length and width. To transform it into a 3D object, you must give it a third dimension that extends out of that plane.
Here's a breakdown:
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2D Shapes: Possess length and width. They are flat and have no thickness. Examples include squares, circles, triangles, and other polygons.
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3D Objects: Possess length, width, and height (or depth). They have volume and take up space. Examples include cubes, spheres, pyramids, and prisms.
| Dimension | 2D (Two-Dimensional) | 3D (Three-Dimensional) |
|---|---|---|
| Dimensions | Length, Width | Length, Width, Height (Depth) |
| Properties | Area | Volume |
| Examples | Square, Circle, Triangle | Cube, Sphere, Pyramid |
| Representation | Drawn on a flat surface (e.g., paper) | Exists in physical space or can be represented in perspective |
Think of it this way:
- Start with a 2D square.
- Extrude (or "pull") that square outwards, giving it a uniform depth.
- The result is a cube – a 3D object. The depth is the defining feature that transitioned it from a 2D to a 3D form.
The flat sides of 3D objects are themselves 2D shapes. For example, a cube is made up of six square faces.
