Question

If `vec(A) = 2 I + j - k , vec(B) = I + 2 j + 3 k` , and `vec(C ) = 6 i - 2 j - 6 k`,then the angle between `(vec(A) + vec(B))` and `vec(C )` will be
A. `30^(@)`
B. `45^(@)`
C. `60^(@)`
D. `90^(@)`

Answer 1

Correct Answer - D
`vec(A) + vec(B) = vec(D) = 3 i + 3j + 2k`
`vec(C ) = 6 i - 2j - 6k`
`vec(D) . Vec(C ) = 18 - 6 - 12 = 0`
`theta = 90^(@)`