\[\begin{array}{l}
Goc\,\,thu\,\,nhat\,\,\,bang\,\,\,{23^0}\\
Tong\,\,\,hai\,\,\,goc\,\,\,can\,\,tim\,\,la:\,\,\,{180^0} - {23^0} = 157{\,^0}.\\
Goi\,\,\,goc\,\,\,thu\,\,\,ba\,\,\,\,la\,\,\,{x^0}\,\,\,\,\left( {0 < x < 157} \right)\\
\Rightarrow goc\,\,\,thuc\,\,hai\,\,\,la:\,\,\,\,13{x^0}.\\
\Rightarrow x + 13x = 157\\
\Leftrightarrow 14x = 157\\
\Leftrightarrow x = \frac{{157}}{{14}} \approx {11^0}12'\\
\Rightarrow Goc\,\,\,thu\,\,hai\,\,la:\,\,\,{145^0}47'.
\end{array}\]
