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GCSE Maths Vector Question Help!







For part C) I don't understand why

EY⃗\vec{EY} = EB⃗\vec{EB} + 23AB⃗\frac{2}{3} \vec{AB}

Why is it not EB⃗\vec{EB} + 25AB⃗\frac{2}{5} \vec{AB}

Because ratio is 2:3
Because with the given ratios BY:AB=2:3BY: AB = 2 : 3.

For AY, we would have BY:AY=2:5BY : AY = 2: 5, which is probably what you are thinking of.
Reply 2
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uer23
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Original post by atsruser
Because with the given ratios BY:AB=2:3BY: AB = 2 : 3.

For AY, we would have BY:AY=2:5BY : AY = 2: 5, which is probably what you are thinking of.


The way I understood it is total is over 5 (2+3) so AB : 2/5 and BY is 3/5.
Original post by uer23
The way I understood it is total is over 5 (2+3) so AB : 2/5 and BY is 3/5.


That's almost correct but AB is longer so AB = 3/5, BY=2/5. so BYAB=2/53/5=?\frac{BY}{AB} = \frac{2/5}{3/5} = \text{?}
Reply 4
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uer23
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Original post by atsruser
That's almost correct but AB is longer so AB = 3/5, BY=2/5. so BYAB=2/53/5=?\frac{BY}{AB} = \frac{2/5}{3/5} = \text{?}


Apologies, yes sorry I meant the other way round.

Thanks but can you explain why did you BYAB=2/53/5\frac{BY}{AB} = \frac{2/5}{3/5} ?
Reply 5
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uer23
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I'm just asking because I done an example earlier where it was slightly different to this



PT⃗=23(b−a)\vec{PT} = \frac{2}{3}(b-a)

TQ⃗=13(b−a)\vec{TQ} = \frac{1}{3}(b-a)
Original post by uer23
I'm just asking because I done an example earlier where it was slightly different to this



PT⃗=23(b−a)\vec{PT} = \frac{2}{3}(b-a)

TQ⃗=13(b−a)\vec{TQ} = \frac{1}{3}(b-a)


Ther you have a point within the vector

On the original it was outside the vector


In the original if AB had been 3c what would BY have been?
Reply 7
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uer23
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Original post by TenOfThem
Ther you have a point within the vector

On the original it was outside the vector


In the original if AB had been 3c what would BY have been?


Oh okay, that makes sense. So for the original question the BY has been extended from original vector ?

2c ?
Original post by uer23
Oh okay, that makes sense. So for the original question the BY has been extended from original vector ?

2c ?


Yes

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