3. In $\square A B C$, condition Jia: $\angle A \cos 2 B > \cos 2 C^{\prime \prime}$. Then Jia is ( ) of Yi.
(A) necessary but not sufficient condition
(B) sufficient but not necessary condition
(C) necessary and sufficient condition
(D) neither necessary condition, nor sufficient condition
3.( C ).

Let $a, b, c, R$ be the three sides and the circumradius of $\triangle ABC$, respectively. From $\angle A1-2 \sin ^{2} B>1-2 \sin ^{2} C$, it follows that $\cos 2 A>\cos 2 B>\cos 2 C$.
The above reasoning is reversible.