If A and B are any two sets, then A ∪ (A ∩ B) is equal to
BC
A
B
A'
A ∪ (A ∩ B) = (A ∪ A) ∩ (A ∪ B) [By distributive law]
⇒ A ∪ (A ∩ B) = A ∩ (A ∪ B) [∵ (A ∪ A) = A ]
⇒ A ∪ (A ∩ B) = A