Two vectors A and B ( aero on them ) are such that |A| ( aero on it ) = 3 and |B| ( aero on it ) =4 and A.B ( aero on them )= -5 , find :
(a) the angle between A and B ( aero on them ).
(b) The length |A+B| and |A-B| ( aero on them both).
(c) the angle between (A+B) and (A-B) ( aero on them both).

I have found (a) and (b) , but i dont know how to find (c) can any one help me ?

Question

Two vectors A and B ( aero on them ) are such that |A| ( aero on it ) = 3 and |B| ( aero on it ) =4 and A.B ( aero on them )= -5 , find :
(a) the angle between  A and B ( aero on them ).
(b) The length |A+B| and |A-B| ( aero on them both).
(c) the angle between (A+B) and (A-B) ( aero on them both).


I have found (a) and (b) , but i dont know how to find (c) can any one help me ?