1. ## Vectors

Can anyone help me with this problem:

2. This is more of a pre-calc or algebra question, just fyi. You can report your own post (use the little triangle symbol with the exclamation mark in it), and a mod will move it for you.

What ideas have you had so far?

3. (ii) Try evaluating the dot product...

4. Any vector that is parallel to $\vec{i}+ 2\vec{j}$ is of the form $a\vec{i}+ 2a\vec{j}$. Any vector that is perpendicular to $3\vec{i}+ \vec{j}$ is of the form $b\vec{i}- 3b\vec{j}$. Find a and b so that $a\vec{i}+ 2a\vec{j}+ b\vec{i}- 3b\vec{j}= \vec{i}+ \vec{j}$