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Vectors C4

Why is my answer to Q1 d) ii) wrong? I understand the method in the answers, which relies on d) i), but I don't see what I've done wrong
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Reply 1
Avatar for Zacken
Zacken
22
[Meh]
(edited 7 years ago)
Can't see anything wrong with your working, other than in the bottom right you should have μ=−2287\mu = -\frac{22}{87}. Note the minus sign. And follow through with that.
Original post by Zacken
How did you get that equation for OX? C does not lie on the line OX, hence it's wrong for you to say OX = OC + whatever. The line OX is quite literally the line passing through both O and X, and C clearly doesn't lie on that line. (Unless X is C, of course - but it isn't).


X looks to be a general point on CD.

OX⃗=OC⃗+CX⃗\vec{OX}=\vec{OC}+\vec{CX}

Then,

OX⃗=OC⃗+μCD⃗\vec{OX}=\vec{OC}+\mu\vec{CD}
Reply 4
Avatar for M14B
M14B
18
Part (d) requires ordinary trigonometry
Reply 5
Avatar for Zacken
Zacken
22
Original post by ghostwalker
X looks to be a general point on CD.

OX⃗=OC⃗+CX⃗\vec{OX}=\vec{OC}+\vec{CX}

Then,

OX⃗=OC⃗+μCD⃗\vec{OX}=\vec{OC}+\mu\vec{CD}


Darn, you're right. That was a dumb move on my part, thanks for clearing it up. Will delete my post to avoid confusion.

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