# c4 vectorsWatch

Thread starter 10 years ago
#1
have this question

The points A and B have position vectors and respectively, relative to a fixed origin.

Find in vector form an equation of the line which passes through A and B

I found the directional vector for this equation which I took vector B away from A getting directional vector which simplifies to

so is the equation r= +s is this correct as the second part asked for the intersection point between this line and another which I know how to do, but came out with odd values which didn't work when i solved the simultaneously.
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10 years ago
#2
Your equation appears to be correct. Perhaps there was a printing error?
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10 years ago
#3
Well, maybe you can post your working for the second half of the question, since that's where you're having trouble?
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Thread starter 10 years ago
#4
okay using the line I have found which we think is right
r=+s and line m from question which is +t

x=1+2s=5+t
y=6-3s=-5-4t
z=4-5s=3+2t

which after so
s=39/23
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10 years ago
#5
I get s = 1.

Try doubling the first equation. Take the third away from it. You get -2 + 9s = 7.
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10 years ago
#6
How did you get to s=39/23, you should get s=1 and t =-2
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