If `vecA=2hati-2hatj-hatk` and `vecB=hati+hatj`, then :
(a) Find angle between `vecA` and `vecB`.
(b) Find the projection of resultant vector of `vecA` and `vecB` on x-axis.
(c) Find a vector which is, if added to `vecA`, gives a unit vector along y-axis.

Answer

D

Explanation

`vec(A).vec(B)=0rArr vec(A)bot vec(B)` & `vec(A).vec(C)=0rArrvec(A) bot vec(C)`
But `vec(B)xxvec(C)` is perpendicular to both `vec(B)` and `vec(C)` so `vec(A)` is parallel to `vec(B)xxvec(C)`