$4.34 \frac{\cos 28^{\circ} \cos 56^{\circ}}{\sin 2^{\circ}}+\frac{\cos 2^{\circ} \cos 4^{\circ}}{\sin 28^{\circ}}=\frac{\sqrt{3} \sin 38^{\circ}}{4 \sin 2^{\circ} \sin 28^{\circ}}$

Calculate (4.35-4.38):


4.34 By combining the fractions on the left side of the equation, we get $\frac{\sin 28^{\circ} \cos 28^{\circ} \cos 56^{\circ}+\sin 2^{\circ} \cos 2^{\circ} \cos 4^{\circ}}{\sin 2^{\circ} \sin 28^{\circ}}=$ $=\frac{\sin 56^{\circ} \cos 56^{\circ}+\sin 4^{\circ} \cos 4^{\circ}}{2 \sin 2^{\circ} \sin 28^{\circ}}=\frac{\sin 112^{\circ}+\sin 8^{\circ}}{4 \sin 2^{\circ} \sin 28^{\circ}}=$ $=\frac{\sqrt{3} \cos 52^{\circ}}{4 \sin 2^{\circ} \sin 28^{\circ}}=\frac{\sqrt{3} \sin 38^{\circ}}{4 \sin 2^{\circ} \sin 28^{\circ}}$.

Here, formulas (4.13), (4.19), and the reduction formulas were used.