What Are Prisms?--Video Captions

What Are Prisms?--Video Captions

Prisms are 3-dimensional figures with special properties.

Specifically, a prism is a polyhedron with two parallel polygon faces and a corresponding number of quadrilateral sides.

Specifically, a prism is a polyhedron with two parallel polygon faces and a corresponding number of quadrilateral sides.

Let's look at an example.

Let's start with a square base.

A square is a regular quadrilateral.

Now, make a copy of this square and translate it vertically, as shown here.

These two squares form the base and top of the prism.

Next, we complete the prism with the rectangular sides.

This is known as a rectangular prism.

It has two square sides and four rectangular sides.

A rectangular prism can also have a rectangular base, like the one shown here.

Many office buildings are examples of rectangular prisms.

Let's look at another example.

Here is an equilateral triangle.

We make a copy and translate the copy vertically.

Then we add the rectangular sides to create a triangular prism.

The roof portion of a house is an example of a triangular prism.

A prism can be constructed using any polygon.

Here is a pentagonal prism.

The base and top are congruent pentagons and the sides are rectangles.

The Pentagon in Washington, DC is an example of a pentagonal prism.

Here is a hexagonal prism.

The base and top are congruent hexagons.

This hexagon-shaped building is an example of a hexagonal prism.

Another way of looking at prisms is to start with a two-dimensional net.

This is a two-dimensional net for a triangular prism.

This flattened version accounts for all the triangular sides, as well as the rectangular.

Imagine a paper version of this net folded as shown to create the three-dimensional prism.

Here is the net for a rectangular prism with a square base.

This sequence shows the folding of it into a rectangular prism.

There is another type of prism that uses triangles rather than quadrilaterals on the side.

These types of prisms are called antiprisms.

Let's take a closer look.

Here is a square.

We'll make a copy of the square and translate it up, but rather than just a translation, we'll add a rotation as shown here.

We'll make a copy of the square and translate it up, but rather than just a translation, we'll add a rotation as shown here.

Next, we add congruent triangular sides.

The complete antiprism looks like this.

Here is a triangular antiprism.

The triangular base and top are colored green and the triangular sides are shown in blue.

Antiprisms can also have other polygon bases.