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Parametric equations - core

Hello I need some help with the following question:

The origin in terms of co ordinate geometry is regarded at the (0,0). I found the values of X which = (3q,0) and Y = (0,4). If O is the origin which = (0,0), and OX=2OY, surely this would mean (0)(3q)=2(0)(4)? Why is this not correct I'm confused :frown:, the value of q=8/3, why ?
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Reply 1
Avatar for TeeEm
TeeEm
19
Original post by Cool-Light
Hello I need some help with the following question:

The origin in terms of co ordinate geometry is regarded at the (0,0). I found the values of X which = (3q,0) and Y = (0,4). If O is the origin which = (0,0), and OX=2OY, surely this would mean (0)(3q)=2(0)(4)? Why is this not correct I'm confused :frown:, the value of q=8/3, why ?


why are you multiplying by zero?!
Reply 2
Avatar for davros
davros
16
Original post by Cool-Light
Hello I need some help with the following question:

The origin in terms of co ordinate geometry is regarded at the (0,0). I found the values of X which = (3q,0) and Y = (0,4). If O is the origin which = (0,0), and OX=2OY, surely this would mean (0)(3q)=2(0)(4)? Why is this not correct I'm confused :frown:, the value of q=8/3, why ?


I don't see where the problem is!

Distance OX = 3q
Distance OY = 4

You're told that OX = 2OY so 3q = 8 and q = 8/3 as required.
Original post by Cool-Light
Hello I need some help with the following question:

The origin in terms of co ordinate geometry is regarded at the (0,0). I found the values of X which = (3q,0) and Y = (0,4). If O is the origin which = (0,0), and OX=2OY, surely this would mean (0)(3q)=2(0)(4)? Why is this not correct I'm confused :frown:, the value of q=8/3, why ?


OX is simply the x coordinate of X, and OY is the y coordinate of Y so OX=2OY is simply saying that 3q=8
Reply 4
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Cool-Light
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Ahhh, I feel like ripping my hair out. I understand bits and pieces, but I don't understand why not simply write X=2Y, rather than writing OX=2OY. I thought I'd substitute the value of X and Y into the equation, and as the origin is (0,0) I'd sub that in also, hence why I thought is multiply it out but this is wrong, why..?
Reply 5
Avatar for TeeEm
TeeEm
19
Original post by Cool-Light
Ahhh, I feel like ripping my hair out. I understand bits and pieces, but I don't understand why not simply write X=2Y, rather than writing OX=2OY. I thought I'd substitute the value of X and Y into the equation, and as the origin is (0,0) I'd sub that in also, hence why I thought is multiply it out but this is wrong, why..?


OX means the distance from O to X i.e. |OX|, which is essentially the actual coordinate of x since we measure from the origin.
:biggrin:
Reply 6
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Cool-Light
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Original post by TeeEm
OX means the distance from O to X i.e. |OX|, which is essentially the actual coordinate of x since we measure from the origin.
:biggrin:

OHHH, mother. Thank youu
Reply 7
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TeeEm
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Original post by Cool-Light
OHHH, mother. Thank youu


no worries ...
keep your hair on
Reply 8
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Cool-Light
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Okay suppose O equals (3,4), would this then mean: 4(3q)=2(12), which would mean 12q=24, therefore q would = 2? Is this the correct way to approach this?
Reply 9
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Cool-Light
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Original post by TeeEm
no worries ...
keep your hair on

LOOL :wink: I'll try too... Last question:
suppose O equals (3,4), would this then mean: 4(3q)=2(12), which would mean 12q=24, therefore q would = 2? Is this the correct way to approach this?
Reply 10
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TeeEm
19
Original post by Cool-Light
LOOL :wink: I'll try too... Last question:
suppose O equals (3,4), would this then mean: 4(3q)=2(12), which would mean 12q=24, therefore q would = 2? Is this the correct way to approach this?


No

then you have to use the distance formula to find an expression for distance(remeber the "square root formula for distance between points" from your C1
Reply 11
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Cool-Light
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Original post by TeeEm
No

then you have to use the distance formula to find an expression for distance(remeber the "square root formula for distance between points" from your C1

I don't remember the equation, but I'm
Just about to google it
Reply 12
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Cool-Light
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Original post by Cool-Light
I don't remember the equation, but I'm
Just about to google it

Ahh I remember this!
Reply 13
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TeeEm
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Original post by Cool-Light
Ahh I remember this!


all good
Reply 14
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Cool-Light
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Original post by TeeEm
all good

I need to put pen to paperand work this out later, currently in a lesson! Just got told off :frown:. Wondering if you could help me later or whenever?
(edited 9 years ago)
Reply 15
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TeeEm
19
Original post by Cool-Light
I need to put pen to paperand work this out later, currently in a lesson! Just got told off :frown:. Wondering if you could help me later or whenever?


I will not unfortunately because I start teaching at 15.30 but I ma sure there many good people around.

all the best.

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