CAn somebody please direct me to a site which can improve my vectors, i can fins when things intersect and equations etc, it is just when the wording gets a bit complicated it gets me
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- Thread Starter
- 11-06-2006 12:48
- 11-06-2006 12:59
haven't you got a textbook? I find vectors are usually pretty well explained in them, if you just do loads of questions.
A few things to remember
AB = OB - OA (O can be any point that is common to the two)
midpoint AB = (1/2)(a+b)
if you've got a line r = a + tb
then the point P on that line such that OP is perpendicular to the line is is the point where the position vector of P is perpendicular to the direction of the line, ie (a + tb) is perpendicular to b. Dot product then = 0 and you can work out the value of t for which this is true.
Vectors represent a movement. I know this is obvious, but it made things much clearer for me when I realised that to get to the midpoint of AB, simply going halfway along AB by using 0.5(OB-OA) won't work because all vectors are given from the point O, and if you performed the movement that would take you halfway from A to B but started at O, you'd end up somewhere else. You have to actually get to A first, and then move halfway.
sorry if all this stuff is ridiculously obvious/doesn't make sense, but it helps me to know what's going on with vectors.