If  are Two Vectors Such That  then Angle Between 

Let  be three unit vectors such that  and  If  makes angles δ, β with  respectively, then  is equal to

Let  be three unit vectors such that angle between  is  If  then cos α + cos β + cos γ = 

Let  be three unit vectors such that angle between  is  If  then cos α + cos β + cos γ = 

Let  be vectors of equal magnitude such that the angle between  Then, the minimum value of the cos α + cos β + cos γ is

Let  be three vectors of equal magnitude such that the angle between each pair is  If   

If , then the value of  is equal to

Angle between vectors  are unit vectors satisfying 

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

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