Numerical: Let A = { 2, 4, 6, 8 } and B = { 6, 8, 10, 12 }. Find A ∩ B. Solution We have A ∩B = { 6, 8 } In the Venn diagram below, area in the green represents A ∩ B
Disjoin sets
If A and B are two sets such that A ∩ B = φ, then A and B are called disjoint sets.
For example, let A = { 2, 4, 6, 8 } and B = { 1, 3, 5, 7 }. Then A and B are called disjoint sets, because there are no elements which are common to A and B
The disjoint sets can be represented by means of Venn diagram below. There is no common area shared by A & B, thus A & B are disjoin sets.
Some Properties of Operation of Intersection( i) A ∩ B = B ∩ A( Commutative law).( ii)( A ∩ B) ∩ C = A ∩( B ∩ C)( Associative law).