Angles, arcs and sectors

1003055102

Level: 
B
The measure of the angle \( \theta \) meets the following conditions: \[\theta\in\bigcup\limits_{k\in\mathbb{Z}}\left\{\frac23\pi+k\frac{\pi}3\right\},\ \theta\in\left[-\frac{\pi}2;2\pi\right].\] Choose the smallest value of $\theta$.
\( -\frac{\pi}3 \)
\( -\frac{\pi}2 \)
\( \frac23\pi \)
\( \frac{\pi}3 \)