Question

find the angle between two vectors a= 2i+j and b=i+2j​

Answer 1

Angle between two vectors is equal to 37°.

a=2i+j

b=i+2j

|a|=✓5

|b|=✓5

dot product of two vectors,

a.b=|a||b| cosθ

4=✓5x✓5 cosθ

cosθ=4/5

θ=37°