Three-dimensional shapes have three dimensions, namely, length, width, and depth. 3D shapes are described by terms such as faces, vertices, and edges as well.
Unlike 2D shapes that are flat shaped, three-dimensional shapes have faces, edges, and vertices. The three dimensions are responsible for the edges of a 3D shape. Have a look at these 2D and 3D figures.
While a 2D shape has height and width, the 3D shape will have height, width, and depth.
In geometrical 3D shapes, faces are the flat surfaces of a shape.
The edges are the lines of the shapes that connect the vertices with one another. Some 3D shapes don’t have edges, such as a sphere or a ball.
3D shapes come with faces, edges, and vertices as the following figure.
The faces are the flat sides, and in the above image, the faces are all squares. The edges are where two faces meet. The vertices are the points as shown in the figure. Based on this figure, we can now easily count the faces, edges, and vertices of 3D shapes.
3D objects that are without any curves have flat surfaces. Flat surfaces are known as plane surfaces as well. Cube, parallelogram, and prism are some of the examples.
3D objects with rounded surfaces have curved surfaces. They have one surface throughout. Spheres such as balls and domes are some examples of curved surfaces.
3D shapes can be differentiated among themselves by these two methods:
When we observe 3D figures, we can sort them on the basis of their surfaces.
The above example is of a cube that has flat surfaces as you can see.
The above example is of a ball which is a sphere and it has a curved surface.
There are some special cases where a 3D shape has both a flat and curved surface.
The above example is of a cylinder which has both the types of surfaces.
Example 1: Which of these 3D shapes have flat surfaces?
Answer: The cubes and the rectangular prisms have flat surfaces. The cylinders have both flat and curved surfaces.
The cone has a flat surface towards the base of the shape.
The circle has no flat surface.
Example 2: How many faces, edges, and vertices do these following shapes have?
b. Rectangular prism
Answer: Let us have a look at these 3D shapes.
The cube has 6 faces, 12 edges, and 8 vertices.
The rectangular prism has 6 faces, 12 edges, and 8 vertices.
The cone has only 1 curved surface, 1 flat surface towards the bottom, 1 edge, and 1 vertex.
Example 3: Which object among the following has 2 flat surfaces.
Answer: If you have a look at the above images, these are some of the objects we come across every day. We have a Rubik’s cube, a ball, a gift, a barrel, and an ice cream cone.
Let us count the flat sides of these objects.
Now, a Rubik’s cube is a cube with 6 flat surfaces.
A spherical ball has 0 flat surfaces.
A rectangular-shaped gift box has 6 flat surfaces.
A cylindrical-shaped barrel has 2 flat surfaces.
An ice cream cone has 0 flat surfaces.
So, the object with 2 flat surfaces is a barrel.
We are surrounded by various 3D objects that we come across every other day. For example, a globe in the library which is spherical in shape, an ice cream cone which is conical in shape, a dice from a board game which is cubical in shape and many more. You can differentiate between these 3D shapes on the basis of their surfaces. If a 3D shape has a flat or curved surface, then you know that it’s a 3D shape. A 2D shape won’t have depth, unlike a 3D shape.
There are many types of 3D shapes with different bases, volumes, and surface areas. Here are a few examples: