\[Дано:\ \ 26{^\circ} < \angle B < 27{^\circ};\ \ \]
\[72{^\circ} < \angle C < 73{^\circ}.\]
\[\angle A = 180{^\circ} - (\angle B + \angle C).\]
\[+ \left| \begin{matrix} 26{^\circ} < \angle B < 27{^\circ} \\ 72{^\circ} < \angle C < 73{^\circ} \\ \end{matrix} \right.\ \]
\[\text{\ \ }\overline{\ \ 98{^\circ} < \angle B + \angle C < 100{^\circ}}\]
\[80{^\circ} < \angle A < 82{^\circ}.\]
\[Ответ:80{^\circ} < \angle A < 82{^\circ}.\]