Quadrant Inequalities
1. **Problem Statement:** Determine the quadrant in which angle $\theta$ lies given the inequalities:
$$\sin(\theta) < 0$$
$$\sin(\theta) \cos(\theta) > 0$$
2. **Recall the signs of sine and cosine in each quadrant:**
- Quadrant I: $\sin(\theta) > 0$, $\cos(\theta) > 0$
- Quadrant II: $\sin(\theta) > 0$, $\cos(\theta) < 0$
- Quadrant III: $\sin(\theta) < 0$, $\cos(\theta) < 0$
- Quadrant IV: $\sin(\theta) < 0$, $\cos(\theta) > 0$
3. **Analyze the first inequality:**
$$\sin(\theta) < 0$$
This means $\theta$ must be in either Quadrant III or Quadrant IV.
4. **Analyze the second inequality:**
$$\sin(\theta) \cos(\theta) > 0$$
Since the product is positive, both $\sin(\theta)$ and $\cos(\theta)$ must have the same sign.
5. **Combine both conditions:**
- From step 3, $\sin(\theta) < 0$ (negative).
- For the product to be positive, $\cos(\theta)$ must also be negative.
6. **Conclusion:**
The only quadrant where both $\sin(\theta)$ and $\cos(\theta)$ are negative is Quadrant III.
**Final answer:** $\boxed{\text{Quadrant III}}$