Math Problem Statement

By using Venn Diagram, prove the following: (i) A ∩ (B ∪ C) = (A ∩ B) ∪ (A ∩ C) (ii) (A ∪ B)^c = A^c ∩ B^c

Solution

To prove these equalities using Venn diagrams, we can break down each statement visually. Here’s the approach and reasoning for each:

(i) A(BC)=(AB)(AC)A \cap (B \cup C) = (A \cap B) \cup (A \cap C)

  1. Left Side ( A(BC)A \cap (B \cup C) ):

    • First, draw the sets AA, BB, and CC.
    • Shade the region representing BCB \cup C (the union of BB and CC).
    • Then, intersect this shaded area with AA, showing only the parts where AA overlaps with BCB \cup C.
  2. Right Side ( (AB)(AC)(A \cap B) \cup (A \cap C) ):

    • Shade the intersection ABA \cap B, showing only the part where AA overlaps with BB.
    • Then, shade the intersection ACA \cap C, showing only the part where AA overlaps with CC.
    • The union of these two shaded areas will illustrate (AB)(AC)(A \cap B) \cup (A \cap C).
  3. Conclusion:

    • The regions obtained from both sides should match, proving that A(BC)=(AB)(AC)A \cap (B \cup C) = (A \cap B) \cup (A \cap C).

(ii) (AB)c=AcBc(A \cup B)^c = A^c \cap B^c

  1. Left Side ( (AB)c(A \cup B)^c ):

    • Draw sets AA and BB and find their union ABA \cup B.
    • The complement (AB)c(A \cup B)^c represents everything outside this union, shading only the area not covered by AA or BB.
  2. Right Side ( AcBcA^c \cap B^c ):

    • Shade AcA^c, which is everything outside of AA.
    • Then, shade BcB^c, which is everything outside of BB.
    • The intersection AcBcA^c \cap B^c is the area that lies outside both AA and BB, matching the region of (AB)c(A \cup B)^c.
  3. Conclusion:

    • The regions obtained from both sides should be the same, thus proving that (AB)c=AcBc(A \cup B)^c = A^c \cap B^c.

Would you like further visual details or any additional clarifications on these proofs?


Here are five related questions that expand upon this topic:

  1. How can you use De Morgan’s laws in other Venn diagram proofs?
  2. Can you explain the difference between the union and intersection in set theory?
  3. What would happen if we introduced a fourth set, DD, in a Venn diagram?
  4. How does the complement of a set change when working with multiple sets?
  5. Can these laws be applied in real-world scenarios, such as probability or logic?

Tip: When working with Venn diagrams, always start with shading individual sets to ensure you clearly see the intersections and unions.

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Math Problem Analysis

Mathematical Concepts

Set Theory
Venn Diagrams
Logical Proofs

Formulas

Distributive Law of Sets
De Morgan's Laws

Theorems

Distributive Property of Intersection over Union
De Morgan's Theorem

Suitable Grade Level

Grades 10-12