Сравните (sin58°*cos52°+sin52°*cos58°)/(cos68°*cos42°-sin42°*sin68°) и (sin48°+cos48°)/(cos24°-sin24°).

\[= \frac{\sin(58{^\circ} + 52{^\circ})}{\cos(68{^\circ} + 42{^\circ})} = \frac{\sin{110{^\circ}}}{\cos{110{^\circ}}} =\]

\[= tg\ 110{^\circ} < 0\]

\[B = \frac{\sin{48{^\circ}} + \cos{48{^\circ}}}{\cos{24{^\circ}} - \sin{24{^\circ}}} > 0;\ \ \]

\[так\ как\sin{48{^\circ}}\ и\ \]

\[\cos{48{^\circ}} > 0 \Longrightarrow\]

\[\Longrightarrow \sin{48{^\circ}} + \cos{48{^\circ}} > 0;\ \ \]

\[для\ \ 0 < a < 45{^\circ} \Longrightarrow\]

\[\Longrightarrow \cos a > \sin a \Longrightarrow\]

\[\Longrightarrow \cos{24{^\circ}} - \sin{24{^\circ}} > 0\]

\[A < B.\]