Lemma 34.2.2.label Let $A$ be a unital $C^{*}$-algebra and $x \in A$ be unitary, then $\norm{x}_{A} = 1$.
Proof. $\normn{x^2}_{A} = \norm{xx^*}_{A} = \norm{1}_{A} = 1$.$\square$
Lemma 34.2.2.label Let $A$ be a unital $C^{*}$-algebra and $x \in A$ be unitary, then $\norm{x}_{A} = 1$.
Proof. $\normn{x^2}_{A} = \norm{xx^*}_{A} = \norm{1}_{A} = 1$.$\square$
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