 # 8.02 Prisms, pyramids, and other 3D solids

Lesson

## Ideas

Being able to identify the  key features of shapes  can help us in this lesson.

### Examples

#### Example 1

How many edges does each shape have?

a
Worked Solution
Create a strategy

We can count the straight lines around the square.

Apply the idea

The square has 4 straight lines around it.

So it has 4 edges.

b
Worked Solution
Create a strategy

We can count the straight lines around the kite.

Apply the idea

The kite has 4 straight lines around it.

So it has 4 edges.

Idea summary

An edge is a straight line that makes part of the perimeter of a shape.

## Prisms

This video looks at prisms, it starts with showing how a prism is made by looking at its net, and then looks at the faces, edges and vertices of a prism.

### Examples

#### Example 2

Here is a rectangular prism.

a

How many faces does it have?

Worked Solution
Create a strategy

Faces are the flat sides of a solid.

Apply the idea

It has 6 faces.

b

How many vertices does it have?

Worked Solution
Create a strategy

Vertices are the corners where edges meet.

Apply the idea

It has 8 vertices.

c

How many edges does it have?

Worked Solution
Create a strategy

An edge is the line where two faces meet.

Apply the idea

It has 12 edges.

Idea summary

A prism can be made with any polygon at its base.

## Pyramids

This video looks at pyramids, it starts with showing how a pyramid is made by looking at its net, and then looks at the faces, edges and vertices of a pyramid.

### Examples

#### Example 3

Here is a square pyramid:

a

How many faces does it have?

Worked Solution
Create a strategy

Faces are the flat sides of a solid object.

Apply the idea

It has 5 faces: the 4 triangles and the 1 square base.

b

How many vertices does it have?

Worked Solution
Create a strategy

Vertices are the corners where two edges meet.

Apply the idea

It has 5 vertices.

c

How many edges does it have?

Worked Solution
Create a strategy

An edge is where two faces meet.

Apply the idea

It has 8 edges.

Idea summary

Pyramids can have different bases, and the name of the base tells us the name of the pyramid.

## Cones, spheres, and cylinders

This video looks at cones, spheres, and cylinders. All these shapes have curved surfaces. Let's see how we can tell which one is which.

### Examples

#### Example 4

Here is a cone.

a

How many curved surfaces does it have?

Worked Solution
Create a strategy

A curved surface is a surface that is not flat.

Apply the idea

There is 1 curved surface that wraps around the circle at base and goes up to the vertex at the top.

b

How many vertices does it have?

Worked Solution
Create a strategy

In a cone, the vertex is the top point.

Apply the idea

It has 1 vertex.

c

How many edges does it have?

Worked Solution
Create a strategy

An edge is a straight line segment where two faces meet.

Apply the idea

It has 1 curved edge around the circle.

Idea summary

Cones, spheres and cylinders all have curved faces.

### Outcomes

#### VCMMG198

Connect three-dimensional objects with their nets and other two-dimensional representations