3. El ángulo \( \frac{2}{5} \pi \mathrm{rad} \) equivale en grados a \( \begin{array}{llll}\text { A. } 30^{\circ} & \text { B. } 36^{\circ} & \text { C. } 72^{\circ} & \text { D. } 108^{\circ}\end{array} \)

\( \frac { \cos \theta + \cos \beta } { \sin \theta - \sin \beta } = \frac { \sin \theta + \sin \beta } { \cos \beta - \cos \theta } \)

5. \( \frac{\sin \theta}{\cos \theta}= \) ? 5. \( \sin ^{2} \theta+\cos ^{2} \theta= \) ?

Points \( A \) and \( B \) are separated by a lake. To find the distance between them, a surveyor locates a point \( C \) on land such than \( \angle C A B=51.4^{\circ} \). Find the distance across the lake from \( A \) to \( B \).

Find the exact value of \( \sin \left(-225^{\circ}\right) \)

2. Определить, сколько целых решений имеет неравенство на интервале \( (0 ; 2 \pi) \). \[ 2 \cos \left(\frac{\pi}{4}-\frac{x}{2}\right) \geq \sqrt{3} \]