题目
曲线 $y = x \sin x + 2 \cos x, (-\frac{\pi}{2} < x < 2 \pi)$ 的拐点是 ?
A. $(0, 2)$
B. $(\pi, -2)$
C. $(\frac{\pi}{2}, \frac{\pi}{2})$
D. $(\frac{3 \pi}{2}, -\frac{3 \pi}{2})$
曲线 $y = x \sin x + 2 \cos x, (-\frac{\pi}{2} < x < 2 \pi)$ 的拐点是 ?
A. $(0, 2)$
B. $(\pi, -2)$
C. $(\frac{\pi}{2}, \frac{\pi}{2})$
D. $(\frac{3 \pi}{2}, -\frac{3 \pi}{2})$