\[\boxed{\text{486\ (486).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[\textbf{а)}\ x \geq 3\]
\(\ \)
\[\textbf{б)}\ y < - 1\]
\(\ \)
\[\textbf{в)}\ 1 < x < 4\ \]
\[\textbf{г)} - 3 \leq y \leq 3\]
\(\ \)
\[\boxed{\text{486.}\text{\ }\text{ОК\ ГДЗ\ -\ домашка\ на\ 5}}\]
\[(x - a)^{2} + (y - 3)^{2} = 16\]
\[\textbf{а)}\ \text{A\ }(2;3):\ \ \]
\[(2 - a)^{2} + (3 - 3)^{2} = 16,\ \ \]
\[(2 - a)^{2} = 16,\ \ a_{1,2} = - 2;6.\ \]
\[\textbf{б)}\ \text{B\ }(7;\ - 1):\ \ \]
\[(7 - a)^{2} + ( - 1 - 3)^{2} = 16,\ \ \]
\[(7 - a)^{2} = 0,\ \ a = 7.\ \]
\[\textbf{в)}\ C\ ( - 2;7):\ \]
\[\ ( - 2 - a)^{2} + (7 - 3)^{2} = 16,\ \ \]
\[( - 2 - a)^{2} = 0,\ \ a = - 2.\]
\[\textbf{г)}\ D\ (1;5):\ \]
\[\ (1 - a)^{2} + (5 - 3)^{2} = 16,\ \ \]
\[(1 - a)^{2} = 12,\ \ \]
\[a_{1,2} = 1 \pm 2\sqrt{3}.\]