Properties of 3D Shapes
Prisms and Pyramids
Hello and welcome to Tutoring Hour!
In this video, we’ll learn about a few solid shapes and discuss their properties.
We live in a three-dimensional world, and our world is filled with endless examples of 3D shapes.
We’ll first take a look at the prisms.
Meet our first solid shape: the rectangular prism.
In some countries, a rectangular prism is called a cuboid.
A rectangular prism has 1, 2, 3, 4, 5, and 6 faces.
The lines where 2 faces meet are called edges.
Let’s figure out the number of edges in a rectangular prism.
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 edges
The point where two edges meet is called a corner, or vertex.
Let’s find out how many vertices there are in a rectangular prism.
There are 1, 2, 3, 4, 5, 6, 7, and 8 corners, or vertices.
Let’s move on to our next prism: the cube.
The 6 identical faces of the cube make it a special rectangular prism.
Let’s find out how many edges there are in a cube.
It has 12 edges.
Let’s find out the number of vertices it has.
There are 8 vertices here.
What’s next?
A triangular prism
It has 5 faces.
A triangular prism has 9 edges.
There are 6 vertices, or corners.
Coming up next is another solid shape: the pentagonal prism.
It has 7 faces.
A pentagonal prism has 15 edges.
It has 10 vertices.
Pause the video; take a look at the hexagonal and octagonal prisms;
and write down the number of faces, edges, and vertices in them.
A hexagonal prism has 8 faces,
18 edges,
and 12 vertices.
An octagonal prism has 10 faces,
24 edges,
and 16 vertices.
Give yourself a pat on the back for getting them right!
Let’s move on to the pyramids.
All pyramids have a base and vertex.
All its side faces are triangles.
Pyramids are named after the shape of their bases.
Let’s take a look at our first pyramid: the triangular pyramid.
It has 4 faces.
It has 1 triangular base and 3 triangular side faces.
A triangular pyramid has 6 edges.
It has 4 vertices.
Our next pyramid has a square base.
No points for guessing its name!
It is a square pyramid.
A square pyramid has 5 faces.
It has a square base and 4 triangular side faces.
A square pyramid has 8 edges.
It has 5 vertices.
Up next is the pentagonal pyramid.
A pentagonal pyramid has 6 faces.
It has a pentagonal base and 5 triangular side faces.
A pentagonal pyramid has 10 edges.
It has 6 vertices.
Let’s take a look at the faces, edges, and vertices of the 3 pyramids.
Do you see a pattern?
The number of side faces is the same as the number of sides in the base.
The total number of faces is the number of sides in the base plus 1.
The number of edges is twice the number of sides in the base.
The number of vertices is the number of sides in the base plus 1.
Let’s use this little trick and quickly fill up the faces, edges, and vertices of the hexagonal pyramid.
The base of a hexagonal pyramid is obviously a hexagon.
It has 6 sides, and the number of faces is 6 plus 1, so we have 7 here.
The number of edges is twice the number of sides in the base, so we’ll write 12 here.
The number of vertices is the number of sides in the base plus 1, so we’ll write 7 here as well.
We’ll quickly do the same for the heptagonal and octagonal pyramids.
A heptagonal pyramid has 8 faces, 14 edges, and 8 vertices;
and an octagonal pyramid has 9 faces, 16 edges, and 9 vertices.
Let’s move on to solid shapes with curved surfaces.
Here comes the cylinder, our next solid shape.
A cylinder has 2 flat faces and a curved surface.
Let’s meet our next shape: the cone.
A cone has 1 flat face and one curved surface.
It has one vertex.
Here comes our last shape: the sphere.
How many edges and vertices do you see here?
A sphere has no edges or vertices.
It has just one curved surface.
That was quite a lot of information.
If you want to put your newfound knowledge to the test,
visit www.tutoringhour.com for practice worksheets.
Smash the like and subscribe buttons and show us some love.
Thanks for watching!
Buh-bye!