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 ).