Anyone want to help a brother out?

Question

juan1857 · Answer

Write -2x+4y=9 in polar form using the polar form of a linear equation.

juan1857 · Answer

all I need help in is getting phi

kittiwitti1 · Answer

equation: $-2x+4y=9$
x and y in polar form: $x=r\cos{\theta}$ and $y=r\sin{\theta}$
so you get $-2x+4y=9\rightarrow-2r\cos{\theta}+4r\sin{\theta}=9$

mathmale · Answer

What are x and y in polar form?  In other words, how would you express x and y in terms of r (radius) and theta (angle)?

juan1857 · Answer

sorry, I should've mentioned I already found p, I'm just not sure when to add or subtract 180 or 360

kittiwitti1 · Answer

...I don't know what $p$ stands for, sorry

juan1857 · Answer

well it is used in the equation
$$p=rcos(\theta-\phi)$$

kittiwitti1 · Answer

Hmm. My professor did not teach us this method...

juan1857 · Answer

all I am having trouble is when I get the Arctan, I don't know when to add or subtract 180 or 360 respectively to its quadrant location

kittiwitti1 · Answer

I am sorry, I've never learned these methods before. I could help you, but I don't know if it will produce the right answer. :(

juan1857 · Answer

its ok, either way I know the answer, but don't know how to get it

kittiwitti1 · Answer

Well, maybe @ganeshie8 can help you ^-^;

juan1857 · Answer

ok thanks

triciaal · Answer

do you have any questions about my response and did you even 
look  at the link I sent before re-posting?

juan1857 · Answer

yeah I actually have

juan1857 · Answer

I just wanted to know when to add or subtract 180 or 360 @triciaal

triciaal · Answer

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