Given that `vec(A)+vec(B)=vec(C )` and that `vec(C )` is perpendicular to `vec(A)` Further if `|vec(A)|=|vec(C )|`, then what is the angle between `vec(A)` and `vec(B)`

The resultant vec(C ) of vec(A) and vec(B) is perpendicular to vec(A) . Also, |vec(A)|=|vec(C )| . The angle between vec(A) and vec(B) is

If vec(A) xx vec(B) = 0 and vec(B) xx vec(C ) = 0 , the angle between vec(A) and vec(C ) is :

Given vec(C )= vec(A) xx vec(B) and vec(D) = vec(B) xx vec(A) . What is the angle between vec(C ) and vec(D) ?

If vec(a) , vec(b), vec(c) are unit vectors such that vec(a) is perpendicular to the plane of vec(b), vec(c) , and the angle between vec(b) and vec(c) is (pi)/(3) Then, what is |vec(a)+vec(b)+vec(c)| ?

If vec(a).vec(b) and vec(c ) are unit vectors such that vec(a) is perpendicular to the plane of vec(b) , vec(c ) and the angle between vec(b) and vec(c ) is (pi)/(3) . Then what is |vec(a) +vec(b)+vec(c )| ?

Given that vec(A)+vec(B)=vec(C ) . If |vec(A)|=4, |vec(B)|=5 and |vec(C )|=sqrt(61) , the angle between vec(A) and vec(B) is

Given that vec(A)+vec(B)=vec(C ) . If |vec(A)|=4, |vec(B)|=5 and |vec(C )|=sqrt(61) , the angle between vec(A) and vec(B) is