Find the value of λ when the projection of 
on 
is 4 units.
Projection of vector 
on vector 
So we first calculate the magnitude of vector b and the scalar product of a vector 
and 
.
Projection of vector 
on vector 
= 4 (1)
Putting the values from above in equation (1),
2λ = 10
λ = 5
1