What is a 3 d shape?

Answer 1

A 3D shape stands for Three-Dimensional. The three dimensions are Height, Width and Depth. A line just has height, so it is 1D. A polygon has both Height and width so it's 2D. A three dimensional object has all three; Height, Width and Depth.

________
^Height/Length = 1D

-------------------
| |
| | <- Height = 2D
| |
-------------------
^ Width
-----------------
-> Depth |
/ |
----------------- | <- Height = 3D
| |
| |
-----------------

^Width