Convert $90^{\circ}$ to radian measure.
- $\dfrac{\pi}{4}$
- $\dfrac{\pi}{3}$
- $\pi$
- $\dfrac{\pi}{2}$
Show answer and solution
Correct answer: D. $\dfrac{\pi}{2}$
**Conversion:** $\theta_{\text{rad}} = \dfrac{\pi}{180^{\circ}} \theta_{\text{deg}}$.
**So $90^{\circ} = \dfrac{\pi}{180} \cdot 90 = \dfrac{\pi}{2}$.**