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Can someone look at this C4 vector question for me please?

frostfly

I seem to get a different value of t when I use a different version of the same vector equation...

Reply 1

frostfly

http://ibb.co/mMC6Cn

http://ibb.co/cdQyQ7

Reply 2

RDKGames

Study Forum Helper

Original post by Mystelle

I seem to get a different value of t when I use a different version of the same vector equation...

And what does that mean exactly...?

I can only assume you're referring to solving something like

r=(1,1) + t(2,0)

and

r=(1,2) + s(-1,2)

which will give a different value of

t

than if you were to solve their alternative parametarisations of

r=(3,1) + t(2,0)

and

r=(2,0) + s(-1,2)

.
The two pairs give different t,s values, but the point of intersection remains the same.

EDIT: Seems to me like this is the case. This is due to picking a different constant vector as part of your equation, or having the direction the other way around. There are infinitely many ways you can write an equation of a line in vector form therefore you can expect to get different values for t,s depending on which you choose. The point of intersection, however, always remains the same so as long as you do it all correctly it doesn't matter at all which parameterisations you choose.