Answer: B
Given: \( r\sin\theta = \frac{7}{2} \) and \( r\cos\theta = \frac{7\sqrt{3}}{2} \) \[ \frac{r\sin\theta}{r\cos\theta} = \frac{\frac{7}{2}}{\frac{7\sqrt{3}}{2}} = \frac{1}{\sqrt{3}} = \tan 30^\circ \Rightarrow \theta = 30^\circ \] \[ r\sin 30^\circ = \frac{7}{2} \Rightarrow r \times \frac{1}{2} = \frac{7}{2} \Rightarrow r = 7 \]
Given: \( r\sin\theta = \frac{7}{2} \) and \( r\cos\theta = \frac{7\sqrt{3}}{2} \) \[ \frac{r\sin\theta}{r\cos\theta} = \frac{\frac{7}{2}}{\frac{7\sqrt{3}}{2}} = \frac{1}{\sqrt{3}} = \tan 30^\circ \Rightarrow \theta = 30^\circ \] \[ r\sin 30^\circ = \frac{7}{2} \Rightarrow r \times \frac{1}{2} = \frac{7}{2} \Rightarrow r = 7 \]