for signs of sine, cosine, tangent.

[ S = 150°, 210° ]

$$x = 360^\circ \cdot k$$ $$x = \pm 60^\circ + 360^\circ \cdot k$$

The language used is clear and concise, making it easy for me to follow along. The formatting is also well-organized, with each exercise and solution presented in a logical and easy-to-read manner.

Solución general: [ x = \frac5\pi6 + 2k\pi \quad \texty \quad x = \frac7\pi6 + 2k\pi ]