If the magnitude of vectors →A, →B and →C are 12, 5 and 13, respectively and →C=→A+→B, then the angle between the vectors →A and →B is
Given →A+→B=→Cand the magnitudes of vectors →A, →B and →C are respectively 12, 5 and 13 units. The angle between →A and →B is
→a,→b and →c be three vectors having magnitudes 1, 1 and 2 respectively. If →a×(→a×→c)+→b=0 , then the acute angle between →a and →c is