Hi All ,

I am trying to create an ARC tangent to 3 curves but I can’t seem to get it like in Rhino .

it always creates it on the inside of the 2 circles . but I need it on the outside of the 2 circles .

I internalized the curves like I want them to be .

Please Help .

Thank you Arc tangent to 3 curves Problem.gh (9.2 KB)

Hi Amir ,

Your definition is interesting ,but it still is not tangent to the circles .

Thank you though .

Hopefully we will get an answer

Hi Yves! I’m having a crack at it. What are your constraints? How “adaptable” should that arc be?

Hi Pietro

The arc can basically be a circle , but I want the 2 circles to be on the inside of the large circle .

The 2 Circles will move diagonally and change size , but they will never go past the straight curve and they will never change sides on X and Y . The size of the large Circle should automatically adapt to the small circle changes and stay tangent . I hope it makes sense .

Thanks for looking at thisArc tangent to 3 curves Problem V2.gh (9.3 KB)

It does! As a matter of fact, turns out we’re not the first ones to try and crack this problem… maybe it’s the first time that it is done in Grasshopper, though. I found out that this particular problem is the Circle-Circle-Line case of the Problem of Apollonius, so you might want to read up a bit about it… I’ll post anything I can come up with!

Here’s the only other occurrence I found, a post by @maje90!

Here instead I found some geometrical constructions but still haven’t managed to replicate them in Grasshopper.

Thank you Pietro ,

I’ll continue to work on it .

Lol, yes, I was already trying that way, @Pietro_Pedone

Unluckly i’m in a rush, i give you an incomplete work.

2 circles and a line can have many cases, in your specific case the 2 circles have the same exact radius, and that is a problem.

Have a look, i’ll continue it this evening.

incomplete.gh (23.1 KB)

Hi Riccardo ,

Thank you so much.

That is exactly what I needed . I don’t even understand how you came up with this , but I will try to .

I have a lot of studying to do .

Thanks again