1.
Two vectors A⃗\vec{A} and B⃗\vec{B} have equal magnitudes. The magnitude of (A⃗+B⃗)(\vec{A} + \vec{B}) is nn times the magnitude of (A⃗−B⃗)(\vec{A} - \vec{B}). The angle between A⃗\vec{A} and B⃗\vec{B} is: