If $A$ is symmetric and involutory, then $A$ is\

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Professor PC Thomas Classes · Answer

(e) $\mathrm{A}^{\mathrm{T}}=\mathrm{A}$\ $\mathrm{A}^{-1}=\mathrm{A}$ $$ \begin{aligned} & A^{-1}=A^{T} \ & A A^{T}=I 	ext { orthogonal } \end{aligned} $$