Weakly Convergent Sequence in Normed Dual Space is Weakly-* Convergent

Theorem
Let $\struct {X, \norm {\, \cdot \,}_X}$ be a normed vector space.

Let $\struct {X^\ast, \norm {\, \cdot \,}_{X^\ast} }$ be the normed dual space of $\struct {X, \norm {\, \cdot \,}_X}$.

Let $f \in X^\ast$.

Let $\sequence {f_n}_{n \mathop \in \N}$ be a sequence in $X^\ast$ converging weakly to $f$.

Then $\sequence {f_n}_{n \mathop \in \N}$ converges weakly-$\ast$ to $f$.

Proof
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