Trigonometric equations and inequalities

1003085802

Level: 
B
The solution set of the inequality \( \mathrm{tg}\, x \leq \frac{\sqrt3}3 \) for \( x\in\mathbb{R} \) is:
\( \bigcup\limits_{k\in\mathbb{Z}}\left(-\frac{\pi}2+k\pi;\ \frac{\pi}6+k\pi\right] \)
\( \bigcup\limits_{k\in\mathbb{Z}}\left(\frac{\pi}6+k\pi;\ \frac{\pi}3+k\pi\right) \)
\( \bigcup\limits_{k\in\mathbb{Z}}\left(-\frac{\pi}2+2k\pi;\ \frac{\pi}6+2k\pi\right] \)
\( \bigcup\limits_{k\in\mathbb{Z}}\left(\frac{\pi}6+2k\pi;\ \frac{\pi}3+2k\pi\right) \)

1003085801

Level: 
B
The solution set of the inequality \( \cos x > 0.5 \) for \( x\in\mathbb{R} \) is:
\( \bigcup\limits_{k\in\mathbb{Z}}\left(-\frac{\pi}3+2k\pi;\ \frac{\pi}3+2k\pi\right) \)
\( \bigcup\limits_{k\in\mathbb{Z}}\left(-\frac{\pi}3+k\pi;\ \frac{\pi}3+k\pi\right) \)
\( \bigcup\limits_{k\in\mathbb{Z}}\left(-\frac{\pi}3+2k\pi;\ k\pi\right) \)
\( \bigcup\limits_{k\in\mathbb{Z}}\left(-\frac{\pi}3+2k\pi;\ 2k\pi\right) \)

1003085705

Level: 
A
Solving the equation \( 2\sin\!\left(x + \frac{\pi}4 \right) = \sqrt3 \) for \( x \), where \( x\in (0; \pi) \), you get:
\( x\in\left\{ \frac{\pi}{12};\frac{5\pi}{12} \right\} \)
\( x\in\left\{ \frac{\pi}{12} \right\} \)
\( x\in\left\{ \frac{3\pi}{12};\frac{5\pi}{12} \right\} \)
\( x\in\left\{ \frac{13\pi}{12};\frac{5\pi}{12} \right\} \)

1003085704

Level: 
A
The solution set of the equation \( \cos\!\left(2x - \frac{\pi}3 \right) = - 0.5 \), where \( 0 < x < 2\pi \), is:
\( \left\{ \frac{\pi}2; \frac{3\pi}2; \frac{5\pi}6; \frac{11\pi}6 \right\} \)
\( \left\{ \frac{\pi}2; \frac{3\pi}2 \right\} \)
\( \left\{ \frac{5\pi}6; \frac{11\pi}6 \right\} \)
\( \left\{ \frac{3\pi}2; \frac{5\pi}6; \frac{11\pi}6; \pi \right\} \)