Proving DeMorgan's Second Rule

1. Jan 11, 2012

seto6

1. The problem statement, all variables and given/known data
Hello, i proved the first demorgan's rule and using that i can easily proof the second one, but i tried to prove it as how i proved the first one. I would like to know what i did is correct, i feel i what i did might not be correct.

2. Relevant equations

(A $\cap$ B)c = Ac $\cup$ Bc

proving through the fact that if;

A=B
then following two should be satisfiable:
A$\subset$B and B$\subset$A

3. The attempt at a solution

2. Jan 12, 2012

micromass

Seems correct!!