Rozwiązanie:
Najpierw obliczymy wyrażenie pod logarytmem:
[tex]$\frac{\sin 15^{\circ}+\cos 15^{\circ}}{\sin 75^{\circ}+\cos{75}^{\circ}} =\frac{\sin 15^{\circ}+\cos 15^{\circ}}{\sin (90^{\circ}-15^{\circ})+\cos (90^{\circ}-15^{\circ})} =\frac{\sin 15^{\circ}+\cos 15^{\circ}}{\sin 15^{\circ}+\cos 15^{\circ}}=1[/tex]
Zatem:
[tex]$\log \Big(\frac{\sin 15^{\circ}+\cos 15^{\circ}}{\sin 75^{\circ}+\cos{75}^{\circ}}\Big)=\log 1=0[/tex]
