Find `| -> a- -> b|,` if two vector ` -> a` and ` -> b` are such that `| -> a|=2,| -> b|=3` and ` -> adot -> b|=4` .

Answer

`sqrt(5)`

Explanation

`|vec(a)-vec(b)|^(2)=(vec(a)-vec(b)).(vec(a)-vec(b))`
`=vec(a).vec(a)-vec(a).vec(b)-vec(b).vec(a)+vec(b).vec(b)`
`=|vec(a)|^(2)-2(vec(a).vec(b))+|vec(b)|^(2)=5`.