Hepatitis B is a viral infection that is primarily transmitted through sexual contact, but it can also be spread through other means such as:
- Contact with infected blood (e.g., sharing needles or other drug paraphernalia).
- From mother to child during childbirth.
- Exposure to contaminated blood products.
If the value of \( \cos \alpha \) is \( \frac{\sqrt{3}}{2} \), then \( A + A = I \), where \[ A = \begin{bmatrix} \sin\alpha & -\cos\alpha \\ \cos\alpha & \sin\alpha \end{bmatrix}. \]