5) \( \cos \frac{\pi}{8} \cdot \cos x-\sin x \cdot \sin \frac{\pi}{8}<-\frac{\sqrt{3}}{2} \)

a) \( \cos ^{2} x-3 \operatorname{sen}^{2} x=0 \) b) \( \cos 2 x=1+4 \operatorname{sen} x \)

6. A camera is filming the progress as a daredevil attempt to scale the wall of a skyscraper. The climber i moving vertically at a constant rate of 15 meters per minute, and the camera is 40 meters from the base of the skyscraper. Through how many radians per minute is the camera angle changing when the climbe is 30 meters feet up the building?

а) Решите неравенство: \( \sin y<-\frac{1}{\sqrt{2}} \)

\( \frac { 1 } { \sec y + \tan y } = \pm f ( x ) \pm g ( x ) \)

Show that \( \frac{\sin \theta}{\operatorname{cosec} \theta-\cot \theta}=1+\cos \theta \)