1. (2004 National College Entrance Examination - Liaoning Paper) If $\cos \theta>0$, and $\sin 2 \theta<0$, then the terminal side of angle $\theta$ is in the ( )
A. First quadrant
B. Second quadrant
C. Third quadrant
D. Fourth quadrant
1. D  From $\cos \theta>0, \sin 2 \theta=2 \sin \theta \cos \theta<0$ we get $\sin \theta<0$, so $\theta$ is in the fourth quadrant.