Calculate center coordinates of circles surrounding a larger circle












0












$begingroup$


I want to draw, say, 8 smaller circles that are adjacent to the big circle the edge of a big circle, similar to this picture.
enter image description here



I know the center coordinates of the bigger circle $(A, B)$, its radius $(R)$,radius of the smaller circles $(r)$, and the number of circles I want to draw $(n)$.



My question is very similar to the one discussed there, with one exception. I want a formula that calculates center coordinates of circles adjacent, not those on the edge of a bigger circle.
Mathematics is not my strongest side (to say the least), so I'd greatly appreciate any help. Thank you!










share|cite|improve this question











$endgroup$












  • $begingroup$
    I think $n$ determines $r$, so for example if you want $6$ externally tangent circles then $r$ is fixed at $r=R$ (all $7$ circles are the same size in that special case). In general, you could write $r$ as a function of $n$ and it would be strictly decreasing.
    $endgroup$
    – Zubin Mukerjee
    Jan 14 at 20:13










  • $begingroup$
    I mention that because you cannot presuppose $n$ and $r$ - most pairs that you choose will lead to impossible situations. Just presuppose $n$ and $R$ and those will together determine $r$.
    $endgroup$
    – Zubin Mukerjee
    Jan 14 at 20:14










  • $begingroup$
    Thank you, that makes sense (in lay terminology, only certain amount of circles of size will fit, correct?)
    $endgroup$
    – Anton Leontyev
    Jan 14 at 20:16










  • $begingroup$
    Connect the centers of the $n$ externally tangent circles and you will have a regular $n$-gon
    $endgroup$
    – Zubin Mukerjee
    Jan 14 at 20:16










  • $begingroup$
    If you choose the number of small circles and the size of the big circle, the size of the small circles is fixed, invariable, set, locked.
    $endgroup$
    – Zubin Mukerjee
    Jan 14 at 20:17
















0












$begingroup$


I want to draw, say, 8 smaller circles that are adjacent to the big circle the edge of a big circle, similar to this picture.
enter image description here



I know the center coordinates of the bigger circle $(A, B)$, its radius $(R)$,radius of the smaller circles $(r)$, and the number of circles I want to draw $(n)$.



My question is very similar to the one discussed there, with one exception. I want a formula that calculates center coordinates of circles adjacent, not those on the edge of a bigger circle.
Mathematics is not my strongest side (to say the least), so I'd greatly appreciate any help. Thank you!










share|cite|improve this question











$endgroup$












  • $begingroup$
    I think $n$ determines $r$, so for example if you want $6$ externally tangent circles then $r$ is fixed at $r=R$ (all $7$ circles are the same size in that special case). In general, you could write $r$ as a function of $n$ and it would be strictly decreasing.
    $endgroup$
    – Zubin Mukerjee
    Jan 14 at 20:13










  • $begingroup$
    I mention that because you cannot presuppose $n$ and $r$ - most pairs that you choose will lead to impossible situations. Just presuppose $n$ and $R$ and those will together determine $r$.
    $endgroup$
    – Zubin Mukerjee
    Jan 14 at 20:14










  • $begingroup$
    Thank you, that makes sense (in lay terminology, only certain amount of circles of size will fit, correct?)
    $endgroup$
    – Anton Leontyev
    Jan 14 at 20:16










  • $begingroup$
    Connect the centers of the $n$ externally tangent circles and you will have a regular $n$-gon
    $endgroup$
    – Zubin Mukerjee
    Jan 14 at 20:16










  • $begingroup$
    If you choose the number of small circles and the size of the big circle, the size of the small circles is fixed, invariable, set, locked.
    $endgroup$
    – Zubin Mukerjee
    Jan 14 at 20:17














0












0








0


1



$begingroup$


I want to draw, say, 8 smaller circles that are adjacent to the big circle the edge of a big circle, similar to this picture.
enter image description here



I know the center coordinates of the bigger circle $(A, B)$, its radius $(R)$,radius of the smaller circles $(r)$, and the number of circles I want to draw $(n)$.



My question is very similar to the one discussed there, with one exception. I want a formula that calculates center coordinates of circles adjacent, not those on the edge of a bigger circle.
Mathematics is not my strongest side (to say the least), so I'd greatly appreciate any help. Thank you!










share|cite|improve this question











$endgroup$




I want to draw, say, 8 smaller circles that are adjacent to the big circle the edge of a big circle, similar to this picture.
enter image description here



I know the center coordinates of the bigger circle $(A, B)$, its radius $(R)$,radius of the smaller circles $(r)$, and the number of circles I want to draw $(n)$.



My question is very similar to the one discussed there, with one exception. I want a formula that calculates center coordinates of circles adjacent, not those on the edge of a bigger circle.
Mathematics is not my strongest side (to say the least), so I'd greatly appreciate any help. Thank you!







geometry circle






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Jan 14 at 20:22









dantopa

6,48942243




6,48942243










asked Jan 14 at 20:07









Anton LeontyevAnton Leontyev

1




1












  • $begingroup$
    I think $n$ determines $r$, so for example if you want $6$ externally tangent circles then $r$ is fixed at $r=R$ (all $7$ circles are the same size in that special case). In general, you could write $r$ as a function of $n$ and it would be strictly decreasing.
    $endgroup$
    – Zubin Mukerjee
    Jan 14 at 20:13










  • $begingroup$
    I mention that because you cannot presuppose $n$ and $r$ - most pairs that you choose will lead to impossible situations. Just presuppose $n$ and $R$ and those will together determine $r$.
    $endgroup$
    – Zubin Mukerjee
    Jan 14 at 20:14










  • $begingroup$
    Thank you, that makes sense (in lay terminology, only certain amount of circles of size will fit, correct?)
    $endgroup$
    – Anton Leontyev
    Jan 14 at 20:16










  • $begingroup$
    Connect the centers of the $n$ externally tangent circles and you will have a regular $n$-gon
    $endgroup$
    – Zubin Mukerjee
    Jan 14 at 20:16










  • $begingroup$
    If you choose the number of small circles and the size of the big circle, the size of the small circles is fixed, invariable, set, locked.
    $endgroup$
    – Zubin Mukerjee
    Jan 14 at 20:17


















  • $begingroup$
    I think $n$ determines $r$, so for example if you want $6$ externally tangent circles then $r$ is fixed at $r=R$ (all $7$ circles are the same size in that special case). In general, you could write $r$ as a function of $n$ and it would be strictly decreasing.
    $endgroup$
    – Zubin Mukerjee
    Jan 14 at 20:13










  • $begingroup$
    I mention that because you cannot presuppose $n$ and $r$ - most pairs that you choose will lead to impossible situations. Just presuppose $n$ and $R$ and those will together determine $r$.
    $endgroup$
    – Zubin Mukerjee
    Jan 14 at 20:14










  • $begingroup$
    Thank you, that makes sense (in lay terminology, only certain amount of circles of size will fit, correct?)
    $endgroup$
    – Anton Leontyev
    Jan 14 at 20:16










  • $begingroup$
    Connect the centers of the $n$ externally tangent circles and you will have a regular $n$-gon
    $endgroup$
    – Zubin Mukerjee
    Jan 14 at 20:16










  • $begingroup$
    If you choose the number of small circles and the size of the big circle, the size of the small circles is fixed, invariable, set, locked.
    $endgroup$
    – Zubin Mukerjee
    Jan 14 at 20:17
















$begingroup$
I think $n$ determines $r$, so for example if you want $6$ externally tangent circles then $r$ is fixed at $r=R$ (all $7$ circles are the same size in that special case). In general, you could write $r$ as a function of $n$ and it would be strictly decreasing.
$endgroup$
– Zubin Mukerjee
Jan 14 at 20:13




$begingroup$
I think $n$ determines $r$, so for example if you want $6$ externally tangent circles then $r$ is fixed at $r=R$ (all $7$ circles are the same size in that special case). In general, you could write $r$ as a function of $n$ and it would be strictly decreasing.
$endgroup$
– Zubin Mukerjee
Jan 14 at 20:13












$begingroup$
I mention that because you cannot presuppose $n$ and $r$ - most pairs that you choose will lead to impossible situations. Just presuppose $n$ and $R$ and those will together determine $r$.
$endgroup$
– Zubin Mukerjee
Jan 14 at 20:14




$begingroup$
I mention that because you cannot presuppose $n$ and $r$ - most pairs that you choose will lead to impossible situations. Just presuppose $n$ and $R$ and those will together determine $r$.
$endgroup$
– Zubin Mukerjee
Jan 14 at 20:14












$begingroup$
Thank you, that makes sense (in lay terminology, only certain amount of circles of size will fit, correct?)
$endgroup$
– Anton Leontyev
Jan 14 at 20:16




$begingroup$
Thank you, that makes sense (in lay terminology, only certain amount of circles of size will fit, correct?)
$endgroup$
– Anton Leontyev
Jan 14 at 20:16












$begingroup$
Connect the centers of the $n$ externally tangent circles and you will have a regular $n$-gon
$endgroup$
– Zubin Mukerjee
Jan 14 at 20:16




$begingroup$
Connect the centers of the $n$ externally tangent circles and you will have a regular $n$-gon
$endgroup$
– Zubin Mukerjee
Jan 14 at 20:16












$begingroup$
If you choose the number of small circles and the size of the big circle, the size of the small circles is fixed, invariable, set, locked.
$endgroup$
– Zubin Mukerjee
Jan 14 at 20:17




$begingroup$
If you choose the number of small circles and the size of the big circle, the size of the small circles is fixed, invariable, set, locked.
$endgroup$
– Zubin Mukerjee
Jan 14 at 20:17










1 Answer
1






active

oldest

votes


















0












$begingroup$

For the 'adjacent' circles use : $delta = 360/n$ where $n$ is the number of circles you want. Then the centers are $c_i = ((R+r)cos idelta + phi, (R+r)sin idelta + phi)$, where $i=0,1,...,n-1$ and $phi$ is some offset rotation. Note that the small circles will not necessarily touch, but they will touch the large circle.



Edit:
Here's a shadertoy example:
https://www.shadertoy.com/view/wsfGWj






share|cite|improve this answer











$endgroup$













  • $begingroup$
    thank you, your comment is of immense help
    $endgroup$
    – Anton Leontyev
    Jan 14 at 20:22










  • $begingroup$
    I just edited it, realized I had already divided by $n$, so check the corrected version. @AntonLeontyev
    $endgroup$
    – lightxbulb
    Jan 14 at 20:25












  • $begingroup$
    Could you please clarify what do you mean by "offset rotation"? Thank you!
    $endgroup$
    – Anton Leontyev
    Jan 14 at 20:29










  • $begingroup$
    @AntonLeontyev check the shadertoy example I gave, the offset is literally what rotates the circles around.
    $endgroup$
    – lightxbulb
    Jan 14 at 20:41










  • $begingroup$
    Thank you so much, now I understand.
    $endgroup$
    – Anton Leontyev
    Jan 14 at 20:50











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1 Answer
1






active

oldest

votes








1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes









0












$begingroup$

For the 'adjacent' circles use : $delta = 360/n$ where $n$ is the number of circles you want. Then the centers are $c_i = ((R+r)cos idelta + phi, (R+r)sin idelta + phi)$, where $i=0,1,...,n-1$ and $phi$ is some offset rotation. Note that the small circles will not necessarily touch, but they will touch the large circle.



Edit:
Here's a shadertoy example:
https://www.shadertoy.com/view/wsfGWj






share|cite|improve this answer











$endgroup$













  • $begingroup$
    thank you, your comment is of immense help
    $endgroup$
    – Anton Leontyev
    Jan 14 at 20:22










  • $begingroup$
    I just edited it, realized I had already divided by $n$, so check the corrected version. @AntonLeontyev
    $endgroup$
    – lightxbulb
    Jan 14 at 20:25












  • $begingroup$
    Could you please clarify what do you mean by "offset rotation"? Thank you!
    $endgroup$
    – Anton Leontyev
    Jan 14 at 20:29










  • $begingroup$
    @AntonLeontyev check the shadertoy example I gave, the offset is literally what rotates the circles around.
    $endgroup$
    – lightxbulb
    Jan 14 at 20:41










  • $begingroup$
    Thank you so much, now I understand.
    $endgroup$
    – Anton Leontyev
    Jan 14 at 20:50
















0












$begingroup$

For the 'adjacent' circles use : $delta = 360/n$ where $n$ is the number of circles you want. Then the centers are $c_i = ((R+r)cos idelta + phi, (R+r)sin idelta + phi)$, where $i=0,1,...,n-1$ and $phi$ is some offset rotation. Note that the small circles will not necessarily touch, but they will touch the large circle.



Edit:
Here's a shadertoy example:
https://www.shadertoy.com/view/wsfGWj






share|cite|improve this answer











$endgroup$













  • $begingroup$
    thank you, your comment is of immense help
    $endgroup$
    – Anton Leontyev
    Jan 14 at 20:22










  • $begingroup$
    I just edited it, realized I had already divided by $n$, so check the corrected version. @AntonLeontyev
    $endgroup$
    – lightxbulb
    Jan 14 at 20:25












  • $begingroup$
    Could you please clarify what do you mean by "offset rotation"? Thank you!
    $endgroup$
    – Anton Leontyev
    Jan 14 at 20:29










  • $begingroup$
    @AntonLeontyev check the shadertoy example I gave, the offset is literally what rotates the circles around.
    $endgroup$
    – lightxbulb
    Jan 14 at 20:41










  • $begingroup$
    Thank you so much, now I understand.
    $endgroup$
    – Anton Leontyev
    Jan 14 at 20:50














0












0








0





$begingroup$

For the 'adjacent' circles use : $delta = 360/n$ where $n$ is the number of circles you want. Then the centers are $c_i = ((R+r)cos idelta + phi, (R+r)sin idelta + phi)$, where $i=0,1,...,n-1$ and $phi$ is some offset rotation. Note that the small circles will not necessarily touch, but they will touch the large circle.



Edit:
Here's a shadertoy example:
https://www.shadertoy.com/view/wsfGWj






share|cite|improve this answer











$endgroup$



For the 'adjacent' circles use : $delta = 360/n$ where $n$ is the number of circles you want. Then the centers are $c_i = ((R+r)cos idelta + phi, (R+r)sin idelta + phi)$, where $i=0,1,...,n-1$ and $phi$ is some offset rotation. Note that the small circles will not necessarily touch, but they will touch the large circle.



Edit:
Here's a shadertoy example:
https://www.shadertoy.com/view/wsfGWj







share|cite|improve this answer














share|cite|improve this answer



share|cite|improve this answer








edited Jan 14 at 20:40

























answered Jan 14 at 20:15









lightxbulblightxbulb

900211




900211












  • $begingroup$
    thank you, your comment is of immense help
    $endgroup$
    – Anton Leontyev
    Jan 14 at 20:22










  • $begingroup$
    I just edited it, realized I had already divided by $n$, so check the corrected version. @AntonLeontyev
    $endgroup$
    – lightxbulb
    Jan 14 at 20:25












  • $begingroup$
    Could you please clarify what do you mean by "offset rotation"? Thank you!
    $endgroup$
    – Anton Leontyev
    Jan 14 at 20:29










  • $begingroup$
    @AntonLeontyev check the shadertoy example I gave, the offset is literally what rotates the circles around.
    $endgroup$
    – lightxbulb
    Jan 14 at 20:41










  • $begingroup$
    Thank you so much, now I understand.
    $endgroup$
    – Anton Leontyev
    Jan 14 at 20:50


















  • $begingroup$
    thank you, your comment is of immense help
    $endgroup$
    – Anton Leontyev
    Jan 14 at 20:22










  • $begingroup$
    I just edited it, realized I had already divided by $n$, so check the corrected version. @AntonLeontyev
    $endgroup$
    – lightxbulb
    Jan 14 at 20:25












  • $begingroup$
    Could you please clarify what do you mean by "offset rotation"? Thank you!
    $endgroup$
    – Anton Leontyev
    Jan 14 at 20:29










  • $begingroup$
    @AntonLeontyev check the shadertoy example I gave, the offset is literally what rotates the circles around.
    $endgroup$
    – lightxbulb
    Jan 14 at 20:41










  • $begingroup$
    Thank you so much, now I understand.
    $endgroup$
    – Anton Leontyev
    Jan 14 at 20:50
















$begingroup$
thank you, your comment is of immense help
$endgroup$
– Anton Leontyev
Jan 14 at 20:22




$begingroup$
thank you, your comment is of immense help
$endgroup$
– Anton Leontyev
Jan 14 at 20:22












$begingroup$
I just edited it, realized I had already divided by $n$, so check the corrected version. @AntonLeontyev
$endgroup$
– lightxbulb
Jan 14 at 20:25






$begingroup$
I just edited it, realized I had already divided by $n$, so check the corrected version. @AntonLeontyev
$endgroup$
– lightxbulb
Jan 14 at 20:25














$begingroup$
Could you please clarify what do you mean by "offset rotation"? Thank you!
$endgroup$
– Anton Leontyev
Jan 14 at 20:29




$begingroup$
Could you please clarify what do you mean by "offset rotation"? Thank you!
$endgroup$
– Anton Leontyev
Jan 14 at 20:29












$begingroup$
@AntonLeontyev check the shadertoy example I gave, the offset is literally what rotates the circles around.
$endgroup$
– lightxbulb
Jan 14 at 20:41




$begingroup$
@AntonLeontyev check the shadertoy example I gave, the offset is literally what rotates the circles around.
$endgroup$
– lightxbulb
Jan 14 at 20:41












$begingroup$
Thank you so much, now I understand.
$endgroup$
– Anton Leontyev
Jan 14 at 20:50




$begingroup$
Thank you so much, now I understand.
$endgroup$
– Anton Leontyev
Jan 14 at 20:50


















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