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+9
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avatar+191 

What is the shortest distance between the circles defined by $x^2-24x +y^2-32y+384=0$ and $x^2+24x +y^2+32y+384=0$? (I already tried but my answer which is $sqrt(24)$ appears to be wrong) Can anybody help please.

 Jul 30, 2021
 #1
avatar+118587 
+2

Hi OrangeJuice.

Welcome to our web2.0calc forum  laugh

 

I have no idea how you got sqrt24 but this is what you need to do

 

1) these are both circles.  So get them into centre-radius form.  Have you done that yet?  What did you get?

 

2) find the distance between the central points - (you should be able to see that the circles do not overlap)

 

3) subrtact the 2 radii.

 

It fell out nicely for me, with no sqrts in the final answer.  I have not checked my answer though.

 

If you want more help then please interact with me.  If I am not around I am sure someone else will fill the void.

 

**

Please no one race in with a final answer.  Teaching answers are usually best.

 Jul 30, 2021
edited by Melody  Jul 30, 2021
 #2
avatar+191 
-5

Hi, it looks like your support is really helpful!

Step 1 results:

 

The distance between the central points is sqrt(24^2+32^2) = 40 and subtracting the distances from the center of the circles gives me 32

After I followed your steps, I got 32 as my final answer and it appears to be correct.

 

P.S. Thanks!

OrangeJuicy  Jul 30, 2021
 #3
avatar+118587 
+2

Yes that is really good.  I am glad my steps helped.

 

I assume you rearranged the circle formulas for yourself ?

 

Here is a pic (which you already know)

 

Melody  Jul 30, 2021
 #4
avatar+118587 
0

OrangeJuice,

 

I have asked you to clarify something that you wrote on this post.  Thanks

 

https://web2.0calc.com/questions/number-theory_82500#r1

 Jul 30, 2021
 #5
avatar+191 
-6

Thanks, and, hopefully my response in the post https://web2.0calc.com/questions/number-theory_82500#r1 will also be clarifying.

OrangeJuicy  Jul 30, 2021

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