\[\boxed{\text{376.}\text{\ }\text{ОК\ ГДЗ\ -\ домашка\ на\ 5}}\]
\[B(a;1 - a)\]
\[\textbf{а)}\ x^{2} - y^{2} = 14\]
\[a^{2} - (1 - a)^{2} = 14\]
\[a^{2} - 1 + 2a - a^{2} = 14\]
\[2a = 15\]
\[a = 7,5.\]
\[При\ a = 7,5.\]
\[\textbf{б)}\ x^{2} + y^{2} = 1\]
\[a^{2} + (1 - a)^{2} = 1\]
\[a^{2} + 1 - 2a + a^{2} = 1\]
\[2a^{2} - 2a = 0\]
\[2a(a - 1) = 0\]
\[a = 0;\ \ a = 1.\]
\[При\ \ a = 0;\ \ a = 1.\ \]