When using the Law of Sines and Cosines, students can often make mistakes that lead to wrong answers. Here are some of the common mistakes to watch out for:

1. Wrongly Identifying Angles and Sides: If you don’t label your angles and sides correctly, it can cause confusion in your calculations. Make sure to double-check your labeling!

2. Using the Wrong Formula: Sometimes, students mix up when to use the Law of Sines ($\frac{a}{\sin A} = \frac{b}{\sin B}$) and the Law of Cosines ($c^2 = a^2 + b^2 - 2ab \cos C$). This can make the problem harder to solve. Remember: use the Law of Sines when you have AAS or ASA situations, and use the Law of Cosines for SSA or SSS.

To avoid these mistakes, keep practicing with different types of triangles and review basic concepts regularly.