For Any Vector                    

The values of ‘a’ for which the points A, B, C with position vectors  respectively are the vertices of a right angled triangle with C = π/2 are 

The vectors  are the adjacent sides of a parallelogram. Then, the acute angle between its diagonals is

If  are two vectors such that  then angle between 

The values of x for which the angle between the vectors  is acute, and the angle between the vector  and the axis of ordinates is obtuse, are

The value of x for which the angle between  and  is obtuse and the angle between  and the z-axis is acute and less than π/6, are  

If  are two unit vectors such that , then the angle between , is 

, then the angle between  

If  are unit vectors and θ is the acute angle between them, then  is a unit vector for

 is equal to