c
Angle between \(\overrightarrow{{A}}\) and \(\overrightarrow{{B}}, \theta=60^{\circ}\)

Angle betwenn \(\overrightarrow{{A}}\) and \(\overrightarrow{{A}}-\overrightarrow{{B}}\)

\(\tan \alpha=\frac{B \sin \theta}{A-B \cos \theta}\)

\(=\frac{B \sqrt{\frac{3}{2}}}{A-B \times \frac{1}{2} 2}\)

\(\tan \alpha=\frac{\sqrt{3} B}{2 A-B}\)