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FP3 Polar Co-ordinates - Help Please !!

http://store.aqa.org.uk/qual/pdf/AQA-MFP3-TEXTBOOK.PDF

Q 5bi and 5bii on page 52 please, I got the rest correct.

I know I am expected to show some working before asking for help, but I am completely stumped by how I am to prove AB is a constant and then find a polar equation for M (mid point of AB).

Thnx
(edited 11 years ago)
Reply 1
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mikelbird
8
perhaps this might help....
Polar Coordinates Problem.pdf35.4KB
Reply 2
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member910132
OP
Original post by mikelbird
perhaps this might help....


PRSOM!

One thing, I don't get how BO = a(1+cos⁡(π+ϕ)) a(1+\cos (\pi + \phi)).
Reply 3
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mikelbird
8
Original post by member910132
PRSOM!

One thing, I don't get how BO = a(1+cos⁡(π+ϕ)) a(1+\cos (\pi + \phi)).


Because AB is a straight line going through O so if the angle for OA is phi radians then surely the angle for B is phi plus pi radians....OK!!
Reply 4
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member910132
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I thought it would be pi take phi if it's on the other side of the straight line.


This was posted from The Student Room's iPhone/iPad App
Reply 5
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mikelbird
8
OK..written in a hurry but cos phi minus pi is also minus cos phi so the result stands...sorry about the confusion
Reply 6
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member910132
OP
Original post by mikelbird
OK..written in a hurry but cos phi minus pi is also minus cos phi so the result stands...sorry about the confusion


Np, I appreciate you going out your way to make the pdf and your time :smile:

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