Dear Mr Maths

Despite having a 1st Class degree in numbers I've got a mental block on the
following - it'll hit me in the face if I sleep on it but I'm tired and no.1
son is asking for help so please would you set me on the right track with
the following....?

OA ---> = a and OB ---> = b

P is a point on AB such that AP = 2PB

Write AP ---> in terms of a and b


Thanks muchly
Jo

On Tue, 19 Apr 2005 23:41:24 +0100, "Jo Richardson"
 wrote:


>Dear Mr Maths
>
>Despite having a 1st Class degree in numbers I've got a mental block on the
>following - it'll hit me in the face if I sleep on it but I'm tired and no.1
>son is asking for help so please would you set me on the right track with
>the following....?
>
>OA ---> = a and OB ---> = b
>
>P is a point on AB such that AP = 2PB
>
>Write AP ---> in terms of a and b
>


I was never brilliant with vectors but looking at it on a diagram
isn't it just 1/3(a-b)? 

Jane
- -

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Jane Willis wrote:

> On Tue, 19 Apr 2005 23:41:24 퍝, "Jo Richardson"
>  wrote:
> 
>> Dear Mr Maths
>> 
>> Despite having a 1st Class degree in numbers I've got a mental block
>> on the following - it'll hit me in the face if I sleep on it but I'm
>> tired and no.1 son is asking for help so please would you set me on
>> the right track with the following....?
>> 
>> OA ---> = a and OB ---> = b
>> 
>> P is a point on AB such that AP = 2PB
>> 
>> Write AP ---> in terms of a and b
>> 
> 
> I was never brilliant with vectors but looking at it on a diagram
> isn't it just 1/3(a-b)?
> 

Don't think so.
AB = AO  OB = -a  b = b - a
AP = 2/3AB = 2/39b - a)
Graham

-- 
GRENMUS
                GrahamHAM@HAMgrenmus.freeserve.co.uk
                Have a HAM sandwich before you reply ;-)
                G. Sumner Ormskirk

Graham wrote:

> Jane Willis wrote:
>> On Tue, 19 Apr 2005 23:41:24 퍝, "Jo Richardson"
>>  wrote:
>> 
>>> Dear Mr Maths
>>> 
>>> Despite having a 1st Class degree in numbers I've got a mental block
>>> on the following - it'll hit me in the face if I sleep on it but I'm
>>> tired and no.1 son is asking for help so please would you set me on
>>> the right track with the following....?
>>> 
>>> OA ---> = a and OB ---> = b
>>> 
>>> P is a point on AB such that AP = 2PB
>>> 
>>> Write AP ---> in terms of a and b
>>> 
>> 
>> I was never brilliant with vectors but looking at it on a diagram
>> isn't it just 1/3(a-b)?
>> 
> Don't think so Jane,
> AB = AO  OB = -a  b = b - a
> AP = 2/3AB = 2/39b - a)
> Graham


Oops bit of a typo there I see.
Should read AP = 2/3(b - a)

-- 
GRENMUS
                GrahamHAM@HAMgrenmus.freeserve.co.uk
                Have a HAM sandwich before you reply ;-)
                G. Sumner Ormskirk

On Wed, 20 Apr 2005 00:20:56 +0100, "Graham"
 wrote:


>AB = AO + OB = -a + b = b - a


See, I told you I was never very good at vectors, I was heading the
wrong way along the line. 

Jane
- -

remove PICKLE to reply to me

"Graham"  wrote in message
news:3cli7nF6bufd7U1@individual.net...
Graham wrote:

> Jane Willis wrote:
>> On Tue, 19 Apr 2005 23:41:24 +0100, "Jo Richardson"
>>  wrote:
>>
>>> Dear Mr Maths
>>>
>>> Despite having a 1st Class degree in numbers I've got a mental block
>>> on the following - it'll hit me in the face if I sleep on it but I'm
>>> tired and no.1 son is asking for help so please would you set me on
>>> the right track with the following....?
>>>
>>> OA ---> = a and OB ---> = b
>>>
>>> P is a point on AB such that AP = 2PB
>>>
>>> Write AP ---> in terms of a and b
>>>
>>
>> I was never brilliant with vectors but looking at it on a diagram
>> isn't it just 1/3(a-b)?
>>
> Don't think so Jane,
> AB = AO + OB = -a + b = b - a
> AP = 2/3AB = 2/39b - a)
> Graham


Oops bit of a typo there I see.
Should read AP = 2/3(b - a)


Thanks Graham - quite simple when you look at it - we did algebra and trig
earlier and I didn't change heads.....

Can go to bed with my Horlicks now...

Cheers
Jo

Jane Willis wrote:

> On Wed, 20 Apr 2005 00:20:56 +0100, "Graham"
>  wrote:
>
>> AB = AO + OB = -a + b = b - a
>
> See, I told you I was never very good at vectors, I was heading the
> wrong way along the line.




does that mean you were off at a tangent?

Janette

<stopping there cos I didn't even understand the question whoosh right over my head>

On Wed, 20 Apr 2005 07:46:44 +0100, "Janette" 
wrote:


>does that mean you were off at a tangent?


It meant I didn't know whether I was coming or going (and you can
delete that smutty thought before you even start to think it)

Jane
- -

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According to :

>> I was never brilliant with vectors but looking at it on a diagram
>> isn't it just 1/3(a-b)?
>> 
>Don't think so.
>AB = AO + OB = -a + b = b - a
>AP = 2/3AB = 2/39b - a)


Ahhhh, it's vectors!  I spent a whole back-of-a-postcard last night
trying to work it out as trig!
-- 
UK Competitions: http://comps.org/

Jane Willis wrote:



> It meant I didn't know whether I was coming or going (and you can
> delete that smutty thought before you even start to think it)



me..................... I am reformed character :-)

Janette

On Wed, 20 Apr 2005 14:27:37 +0100, "Janette" 
wrote:


>Jane Willis wrote:
>
>
>> It meant I didn't know whether I was coming or going (and you can
>> delete that smutty thought before you even start to think it)
>
>
>me..................... I am reformed character :-)


I thought you'd been quite for a while - been locked away for
reporogramming then?

Jane
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