Which of the following can be written as \( \sin 9 x \) ? \( \begin{array}{l}\sin 5 x \cos 4 x-\cos 5 x \sin 4 x \\ \sin 5 x \cos 4 x+\cos 5 x \sin 4 x \\ \cos ^{2} 5 x-\sin ^{2} 4 x \\ 0 \cos ^{2} 5 x+\sin ^{2} 4 x \\ \text {-out of } 1 \\ \text { Previous page }\end{array} \) P

Simplify the following expressions \( 6.1 \quad \frac{\sin 210^{\circ} \cos 300^{\circ} \tan 240^{\circ}}{\cos 120^{\circ} \tan 150^{\circ} \sin 330^{\circ}}\left[\begin{array}{l}{[\sin (-\theta)+\cos (360-\theta)]}\end{array}\right. \) If \( \tan x=m+\frac{1}{m}, 90^{\circ} \leq \) Calculate the value of \( x \)

Choose the correct answer from those given : \( \begin{array}{llll}\text { (1) In the opposite figure : } \\ \theta= \\ \begin{array}{llll}\text { (a) } 10^{\circ} & \text { (b) } 20^{\circ} & \text { (c) } 40^{\circ} & \text { (d) } 80^{\circ}\end{array}\end{array} \).

14. Use the basic identities to find the values of the other five trigonometric functions given \( \sin x=-\frac{1}{2} \) and the angle \( x \) in the \( 4^{\text {th }} \) quadrant.

b. Se \( \alpha=-\frac{\pi}{2} \rightarrow \cos \alpha=0 \) esin \( \alpha=4 \). Aiutandoti con la circonferenza goniometrica, stabilisci se i seguenti valori sono positivi, negativi o nulti, \( \sin \left(-\frac{5}{2} \pi\right) ; \cos \frac{7}{6} \pi ; \sin 380^{\circ} ; \cos 452^{\circ} ; \sin 7 \pi ; \cos \left(-170^{\circ}\right) \).

\( 5.1 . \frac { \sin 210 ^ { \circ } \cos 300 ^ { \circ } \tan 240 ^ { \circ } } { \cos 120 ^ { \circ } \tan 150 ^ { \circ } \sin 330 ^ { \circ } } \)