" 12.सिद्ध Do that "A sub phi rArr A=phi

Prove that A sub phi rArr A=phi

Prove that A sub phi implies A =phi .

Prove that : phi- A= phi .

Determine the truth of falsity of the A sub phi "if and only if "A = phi propositions with reasons.

tan phi cos ec phi=sec phi

If A sub U , prove that : (i) U' =phi (ii) phi' =U (iii) (A')' =A (iv) A cup A' =U (v) A cap A' =phi

Determine if A sub B or A cancel sub B where A=phi, B ={phi}

In a binary operation **: phi xx phi rarr phi is defined as a ** b = (ab)/4, a , b in phi . Show that ** is associative.

Given two sets A and B,A sub B iff A backslash B=phi