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Confused with Graphing Polar Coordinates

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Forgive me if this question sounds stupid, but I am supposed to graph $$r=8\cos\left(\theta \right)$$, and I think it is supposed to make a circle? However, when I try to graph it using the table I have given, I end out with an infinity sign, and I'm not sure why?

Any help would be greatly appreciated!

Apr 24, 2020

#1
+109492
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I am very rusty on this topic so I can't help at all without doing some 'homework'

Here is a video I am watching that might help with an introduction.

Apr 24, 2020
#2
+109492
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Here is a site that will definitely help.

https://www.mathway.com/popular-problems/Algebra/884633

Press on the arrow and it will fill in the steps

Apr 24, 2020
#3
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Thank you for the help!

Unfortunately, I can not get the "view steps" in Mathway to work without making an account, which costs money. Additionally, the first link does not bring me to a video, just to google search :/

Apr 24, 2020
#4
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The first video is what I think Melody wants you to see. As to Mathway, it is blocked on my browser :/

AnExtremelyLongName  Apr 24, 2020
#5
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In that case, I have already watched that video, and still do not understand. It goes over the graphing part very quickly, and I do not get it's explanation of having a negative r value in an $$(r,\theta)$$ coordinate.

Guest Apr 24, 2020
#8
+109492
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I am sorry, I did not look very far in Mathway and did not realize there was cost involved.

this is the first video. See if it works now

Melody  Apr 25, 2020
#6
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Remember that a negative r value means that the distance must be measured "through the pole".

Therefore, if you have an angle that puts the point into the 2nd quadrant, you must put the point in the 4th quadrant.

This is true for all points ... quadrant 1 points get placed into quadrant 3; quadrant 3 points get placed into quadrant 1,

I'll bet (but not too much, 'cause I'm cheap) that, because the full graph is done by the time you get to 180o (or pi),

and repeats the picture again, you're putting the second half of the points in quadrants 2 and 3, when they should

be placed in quadrants 1 and 4.

Think about what the negative r-value means.

Apr 24, 2020
#7
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Thank you so much!!! I retried it using your method and have gotten it to work now. I think I was confsued because my teacher had said that to graph a negative r value, you do $$\left|r\right|$$, and make $$\theta$$ go clockwise, but maybe I misunderstood them.

Guest Apr 24, 2020