Найдите $\cos 75^{\circ} .$

Задание 13.23

Найдите $\cos 7 5^{∘} .$

\cos 75 = \cos (30 + 45) = \cos 30 \cos 45 - \sin 30 \sin 45 =

= \frac{\sqrt{3}}{2} \cdot \frac{\sqrt{2}}{2} - \frac{1}{2} \cdot \frac{\sqrt{2}}{2} = \frac{\sqrt{6} - \sqrt{2}}{4}

gimli

2021-11-20 11:38