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Math HELP!

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chapz
Posts: 10182 - Karma: 66
hey guys, so im having trouble converting this polar equation into a cartesian equation. please help! its probably really easy, i just am brain fried at this point. btw im using x as a variable, but it should be theta....

r = 1 / (1 - sin(x)) -> needs to be in terms of x and y.

x=rcos(x)
y=rsin(x)
Feb 26 2010 12:05AM
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epoxiedtip
Posts: 535 - Karma: 56
tuturvista.com
Feb 26 2010 12:07AM
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corona
Posts: 12801 - Karma: 32,780
all I can see you getting is y= r-1
Feb 26 2010 12:10AM
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00_Koda
Posts: 922 - Karma: 270
i just wanna say fuck math its my weakness, the end.
Feb 26 2010 12:11AM
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corona
Posts: 12801 - Karma: 32,780
oh fuck the x as theta messed me up.. oops
Feb 26 2010 12:12AM
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corona
Posts: 12801 - Karma: 32,780
does this work? (using z as theta to not get confused)

r= 1/(1-sinz)
r= 1/(cosz^2+sinz^2-sinz)
rcosz^2+rsinz^2-rsinz = 1
= x^2 + y^2 - y -1
Feb 26 2010 12:22AM
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chapz
Posts: 10182 - Karma: 66
what identity did you use from the original to the second step?
Feb 26 2010 12:28AM
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corona
Posts: 12801 - Karma: 32,780
that
1 = cosx^2 + sinx^2
Feb 26 2010 12:32AM
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chapz
Posts: 10182 - Karma: 66
mhm, well if i graph the original and yours, theyre different which isnt a great sign haha

but i think the problem is you put rsin^2(z) = y^2, i think it has to be r^2 and sin^2 to work no?
Feb 26 2010 12:38AM
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corona
Posts: 12801 - Karma: 32,780
maybe, what did you set r as when you graphed it?
Feb 26 2010 12:44AM
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chapz
Posts: 10182 - Karma: 66
the original function, and then i tried yours with the x and y(using cartesian notation) and it didnt give the same graph! frig i hate this. its the only problem i cant seem to get! thanks for all your help though!
Feb 26 2010 12:49AM
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