☼ Important  Results  From  Venn Diagrams ( As shown in Case – I )  :   Let  A and  B be any two intersecting sets.

(i) n (A  B)  =  n (A) + n (B) – n (A  B)

(ii) n (A  B)  =  n (A) + n (B)     ;    when,  A  B  = .

(iii) n (A – B) + n (A  B)  =  n (A)

(iv) n (B – A) + n (A  B)  =  n (B)

(v) n (A – B) + n (A  B) + n(B – A)  =  n (A  B)

vi) For three sets A, B and C,

n (A  B  C)

=   n (A) + n (B) + n (C)

–  n (A  B) –  n (B  C)

– n (C  A)

+ n (A  B  C)

Click to next