Propositional and First Order Logic GATE-CS-2006

Question

In the question whether this statement is a tautology ((A ∨ B) → C)) ≡ ((A → C) ∨ (B → C))  ,

If I take first part ((A ∨ B) → C)) as P and second part  ((A → C) ∨ (B → C)) as Q , do I need to prove P-->Q is true? or both P-->Q and  Q-->P as true? I am confused about the ≡ symbol.

Comments

$((A \vee B)\rightarrow C) \\ \equiv (\sim(A \vee B)\vee C)\\ \equiv ((\sim A \wedge \sim B)\vee C)\\ \equiv ((\sim A \vee C)\wedge(\sim B \vee C)\\ \equiv (A \rightarrow C)\wedge(B\rightarrow C)$

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\equiv   the triple bar is used as a symbol of identity.

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The first three lines (3rd line to be precise) of wiki page of Logical Biconditional has the answer of your question.