Transform the following polar equation into an equation in rectangular coordinates: r = 4
A. (x - 4)2 + y2 = 4
B. x = 4
C. xy = 16
D. x2 + y2 = 16

Question

Transform the following polar equation into an equation in rectangular coordinates: r = 4
 		A.	(x - 4)2 + y2 = 4
 		B.	x = 4
 		C.	xy = 16
 		D.	x2 + y2 = 16

jhannybean · Answer

Is it just r = 4? Or is there more to it...

anonymous · Answer

It's just r=4

jhannybean · Answer

Alright. Let me try working this out myself first. One second. :)

jhannybean · Answer

Alright, you understand that the equation of a circle in polar coordinates is $x^2 +y^2 = r^2$ right?

anonymous · Answer

Right

jhannybean · Answer

Now we're already given $r=4$, and to fit this form for the equation of a circle in polar coordinates , what would we have to do to r?

anonymous · Answer

Square it?

jhannybean · Answer

Yes! :) 

that means $ r^2 = 4^2 \implies r^2 = 16$

jhannybean · Answer

Now that we've got $r^2 = 16$ and  $x^2 +y^2 =r^2$, so which answer choice do you think it would be? :)

anonymous · Answer

Got it. Thanks!

jhannybean · Answer

Awesome! :) Good job .