Mathematics Quick Revision of sets from Key Diagrams
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### Venn Diagram

• A \color{blue} ul(\mathtt ( \ \ VENN \ \ Diagram)) is a diagram that uses closed curves to illustrate the relationships among sets.

• These diagrams consist of rectangles and closed curves usually circles or ellipses. The universal set is represented usually by a rectangle and its subsets by circles or ellipses.

E.g. 1 : In Fiig.1 \ \  U = {1,2,3, ..., 10} is the universal set of which A = {2,4,6,8,10} is a subset.

### Union of sets

"Definition" The union of two sets A and B is the set C which consists of all those elements which are either in A or in B (including those which are in both).

we write A ∪ B and usually read as "‘A union B’."

### Intersection of sets

• The intersection of two sets A and B is the set of all those elements which "belong to both A and B."

• The symbol ‘∩’ is used to denote the intersection.

star \ \ "Disjoint sets"

• If A and B are two sets such that A ∩ B = Phi , then A and B are called disjoint sets.

### Difference of sets (A-B) or (A/B) :

• The difference of the sets A and B in this order is the set of elements which  "belong to A but not to B."

• Symbolically, we write A – B and read as "“ A minus B”"

### Complement of a Set

• Let U be the universal set and A a subset of U. Then the complement of A is the set of all elements of U which are not the elements of A.

• Symbolically, we write A′ to denote the complement of A with respect to U.