Question

The angle between vectors ā = 2î - j+k and b =î-j is
(A) 0°
(B) 30°
(C) 60°
(D)90°​

Answer 1

a=2i-j+k

b=i-j

dot product of a and b

a.b=2-1

=1

magnitude of a=√6

magnitude of b=√2

a.b=|a|×|b|cosØ

and Ø is the angle between vectors

therefore,

1=√6×√2×cosØ

cosØ=1/√12

Ø=cos^-1(1/√12)

hope it helps

Answer 2

Explanation:

refer the above pic....