posted by Nat .
the components of a vector V can be written (Vx,Vy,Vz). what are the components and length of a vector which is te sum of the 2 vectors, V1 and V2, whose components are (8,-3.7,0) and (3.9,-8.1,-4.4)?
Add the corresponding components to get the components of the sum vector.
The length is the square root of the sum of the squared components
how do i find the angle between the summed vector and the z axis in this reference frame?
The cosine of that angle is vertical component divided by the vector length.
They don't ask for that angle in your original question