Question

please answer this question with full explanation​

Answer 1

Answer:

90 degrees

Explanation:

Formula Used  [Dot product of vectors] : A.B = ABcos∅

We know that if X = ai + bj + ck and Y = pi +qj +rk

Therefore X.Y = (a×p) + (b×q) + (c×r)

So in our question, A.B = (1 × -1) + (1 × -1) + (1 × 2) = 0

So we get

A.B = ABcos∅

0 = ABcos∅

cos∅ = 0

∅ = 90 degrees

[Here we could have found out magnitude of AB but since LHS = 0 it is not required}