JAMB Mathematics 2018 Paper

Concept:The signs of trigonometric ratios help identify the quadrant where an angle lies.Explanation:In the first quadrant, $\sin \theta$, $\cos \theta$, and $\tan \theta$ are all positive.In the second quadrant, only $\sin \theta$ is positive, while $\cos \theta$ and $\tan \theta$ are negative.In the third quadrant, $\tan \theta$ is positive, but $\sin \theta$ and $\cos \theta$ are both negative.In the fourth quadrant, only $\cos \theta$ is positive, while $\sin \theta$ and $\tan \theta$ are negative.We need $\tan \theta > 0$ and $\sin \theta < 0$.This exact sign combination appears only in the third quadrant.Therefore, the angle $\theta$ lies in the third quadrant only.Answer:Third only (Option B).