Question

How do you find the projection of u=<4,8> onto v=<-1,2>?

Answer 1

`(-12/5, 24/5)`

Explanation:

`u * v = ||u|| * ||v|| * cos theta`

But you want `||u|| * cos theta * hat v = frac{u * v}{||v||} * frac{v}{||v||} = frac{u*v}{v*v}*v`

`= frac{4(-1) + 8*2}{(-1)^2 + 2^2} * (-1, 2)`

`= frac{12}{5} * (-1, 2)`