\(\sqrt{x^2-8x+16}-2=3\\ \Leftrightarrow\sqrt{\left(x-4\right)^2}=3+2\\ \Leftrightarrow \left|x-4\right|=5\\ \Leftrightarrow\left\{{}\begin{matrix}x-4=5\\x-4=-5\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}x=9\left(TM\right)\\x=-1\left(KTM\right)\end{matrix}\right.\)