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, \( \sin \left(-\frac{5}{2} \pi\right) ; \cos \frac{7}{6} \pi ; \sin 380^{\circ} ; \cos 452^{\circ} ; \sin 7 \pi ; \cos \left(-170^{\circ}\right) \).

Drow the graph of \( J=\tan \left(2 x+90^{\circ}\right) \) for \( x \in\left[-90^{\circ} ; 90^{\circ}\right. \)

\( [ \sin ( - \theta ) + \cos ( 360 - \theta ) ] [ \cos ( 90 - \theta ) + \frac { \sin \theta } { \tan \theta } ] \)

If \( \tan x=m+\frac{1}{m}, 90^{\circ} \leq x \leq 270^{\circ} \) and \( m^{2}+\frac{1}{m^{2}}=1 \) Calculate the value of \( x \) without the use of a calculator.

\[ \cos 9 x \cdot \cos ^{3} x-\sin 9 x \cdot \sin 3 x=\sin 4 x \] denkleminin en küçük pozitif kökü kaç derecedir? \( \underbrace{\text { A) } 6} \) \( \begin{array}{llll}\text { B) } 8 & \text { C) } 9 & \text { D) } 10 & \text { E) } 12\end{array} \)

\( \sin \frac { \sin \theta } { 1 + \cos \theta } = \frac { 1 - \cos \theta } { \sin \theta } \)