Lesson 90: Sets
Part 2
Objectives:
1. Students use set notation to indicate sets of numbers.
2. Students find the unions and intersections of sets.
3. Students determine whether a set is a subset of another set.
4. Students draw Venn diagrams to illustrate relationships among sets.
Definitions:
1. set: is a collection of elements
2. subset: a part of a set
Think of some examples of subsets that are not necessarily mathematical.
1.
2.
3.
Example: Use the subset symbol to show the relationship between the set of natural
numbers and the set of integers.
What is another name for natural numbers?
Here are some tricks to remember which symbol goes with which set of numbers:
Venn Diagrams: easily show the relationships among sets
Intersection
What are some examples of intersections that are not necessarily mathematical?
1.
2.
3.
Union
What are some examples of intersections that are not necessarily mathematical?
1.
2.
3.
Example: Set A and B are shown below. Find A  B and A  B.
A = {1,2,3,4}
B = {2,4,6,8}
Empty set: no elements in the intersection of two sets
Name two sets in which the intersection is the empty set.
What are some examples of empty sets that are not necessarily mathematical?
1.
2.
3.
Set Notation Symbols
{}
The set of
Is an element of

Is a subset of

The intersection of

The union of

Empty set

Example: Use a Venn Diagram to illustrate the sets. Find A  B.