Question

Pls answer the following question

Answer 1

the angle between two vectors is
found by

let a and b two vector then angle between them
cos∅ = a.b/|a| |b|

cos∅ = ratio of dot product of two vectors and product of its magnitude .

now,

cos∅ = A.B/|A||B|
=(i + j ).( i -j)/√2.√2
=(1 -1)/2

=0

cos∅ = cosπ/2

∅ = π/ 2

Answer 2

see attachment............