The angle between vector (\( \vec{A} \)) and (\( \vec{A} - \vec{B} \)) is:
\( \tan^{-1}\!\left(\dfrac{-B/2}{A - B\sqrt{3}/2}\right) \)
\( \tan^{-1}\!\left(\dfrac{A}{0.7B}\right) \)
\( \tan^{-1}\!\left(\dfrac{\sqrt{3}B}{2A - B}\right) \)
\( \tan^{-1}\!\left(\dfrac{B\cos\theta}{A - B\sin\theta}\right) \)