If \( \cos \theta=-\frac{1}{2} \), then \( \cos (-\theta)=\square \)

The cosine function is an even function, meaning that \( \cos(-\theta) = \cos(\theta) \). Given that \( \cos \theta = -\frac{1}{2} \), we can directly deduce that \( \cos(-\theta) = -\frac{1}{2} \) as well. Therefore, the answer is \( -\frac{1}{2} \). Knowing that cosine is an even function helps simplify problems quickly, especially when working with negative angles. So next time you encounter a negative angle, remember that flipping the sign of the angle doesn’t change the cosine value! If you're interested in diving deeper into trigonometry, consider exploring topics like the unit circle or the various trigonometric identities. These concepts can provide a more comprehensive understanding of how the functions behave in different quadrants and scenarios!