Hi I have this problem (attached) and I really need some brush up on vectors. Can you suggest a link for some good notes or tutorials that tackles part b) and c) .
2 lines are perpendicular if their direction vector are perpendicular (dot product equal to 0)
2 lines intersect if you can find one value for and one for such that the coordinates are equal
l1 and l2 intersect and are perpendicular ; in the plane formed by l1 and l2 place A, P and B