Which of these figures are prisms, and which are not?

Question

Sort these figures. Which are prisms? That is, which figures have repeating layers of the same base?
Prisms Not Prisms
3D shape with 2 trapezoidal bases connected by rectangular faces.
3D shape with 2 triangular bases connected by rectangular faces.
3D figure with octagonal base and eight triangular faces meeting at a point.
3D figure with rectangular base with four triangular faces meeting at a point.
3D shape with 2 pentagonal bases connected by rectangular faces.

Answer 1

To determine which figures are prisms, we look for those that have two parallel bases of the same shape and are connected by rectangular or parallelogram faces. Here’s how the figures you listed classify:

Prisms:

1. 3D shape with 2 trapezoidal bases connected by rectangular faces.
2. 3D shape with 2 triangular bases connected by rectangular faces.
3. 3D shape with 2 pentagonal bases connected by rectangular faces.

Not Prisms:

1. 3D figure with octagonal base and eight triangular faces meeting at a point (this is a pyramid).
2. 3D figure with rectangular base and four triangular faces meeting at a point (this is also a pyramid).

So, the sorted classification is:

Prisms:

• 3D shape with 2 trapezoidal bases connected by rectangular faces.
• 3D shape with 2 triangular bases connected by rectangular faces.
• 3D shape with 2 pentagonal bases connected by rectangular faces.

Not Prisms:

• 3D figure with octagonal base and eight triangular faces meeting at a point.
• 3D figure with rectangular base and four triangular faces meeting at a point.