Convert \( 210^{\circ} \) to radian measure in terms of \( \pi \).

To convert degrees to radians, you can use the conversion factor \( \frac{\pi \text{ radians}}{180^{\circ}} \). For \( 210^{\circ} \): \[ 210^{\circ} \times \frac{\pi \text{ radians}}{180^{\circ}} = \frac{210\pi}{180} \] Now, simplify \( \frac{210}{180} \): \[ \frac{210}{180} = \frac{21}{18} = \frac{7}{6} \] So, \( 210^{\circ} \) in radian measure is: \[ \frac{7\pi}{6} \text{ radians} \]