The Vectors  are The Adjacent Sides Of A Parallelogram. Then, The Acute Angle Between Its Diagonals Is

If two out of the three vectors  are unit vectors such that  then the length of the third vector is   

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 

If  are two vectors such that  then angle between