topic Re: CIRCLE TANGENT TO THREE LINES??? CANYOU DO IT? in Modeling

CIRCLE TANGENT TO THREE LINES??? CANYOU DO IT?

Anonymous — Fri, 21 May 2004 09:14:46 GMT

Can anybody tell me how to draw a circle tangent to three lines or other circles?
I didn't know where to post this question - to Tips and tricks or to Wishes. Or to Wishes never to be...
Every time I need to do it I switch to AutoCAD and copy it back to AC.
So, you can do it in AutoCAD guys...

Re: CIRCLE TANGENT TO THREE LINES??? CANYOU DO IT?

Anonymous — Fri, 21 May 2004 11:34:09 GMT

I think this would be good to post to the wish list, but I would expand it to request more drawing methods in general. Like drawing a line that is tangent to two (existing) circles. There must be more but I can't think of them off the top of my head.

Please do post this one (or I will). It would be great to get everyone adding their own missing methods to the list.

BTW: There probably is some way to construct the solution (I haven't the time right now to noodle it out), but you are right, this should just take three clicks. We are (mostly) trying to practice architecture not Pythagorean geometry.

Re: CIRCLE TANGENT TO THREE LINES??? CANYOU DO IT?

Laszlo Nagy — Fri, 21 May 2004 12:16:45 GMT

This is how to create a tangent to two circles
Laszlo

Re: CIRCLE TANGENT TO THREE LINES??? CANYOU DO IT?

Djordje — Fri, 21 May 2004 12:21:53 GMT

Ladies and gentlement,

the tangent discussion happened extensively at the end of the old Talk and the birth of this one; consequesntly, a well illustrated tips by Alex Schamenek and Stuart James had been posted in the Tips&Tricks forum. Look for the end of last year dates.

Before you post, pleasee read first; search here, and at ArchiGuide. Post only after that. Otherwise a valuable contribution can be lost in the redundant threads. Never mind making my life easier

Re: CIRCLE TANGENT TO THREE LINES??? CANYOU DO IT?

Laszlo Nagy — Fri, 21 May 2004 13:16:00 GMT

I think the circle tangent to three line solution was not yet posted.
Here it is.
Laszlo

Re: CIRCLE TANGENT TO THREE LINES??? CANYOU DO IT?

Laszlo Nagy — Fri, 21 May 2004 13:16:52 GMT

Here is another one that is a specialized case of the previous one.
Laszlo

Re: CIRCLE TANGENT TO THREE LINES??? CANYOU DO IT?

Anonymous — Fri, 21 May 2004 13:32:15 GMT

Thank you Laszlo. Handy methods and easily remembered.

Re: CIRCLE TANGENT TO THREE LINES??? CANYOU DO IT?

Djordje — Fri, 21 May 2004 15:21:46 GMT

laszlonagy wrote:
I think the circle tangent to three line solution was not yet posted.

Yep, you are right!

Going to Tips&Tricks now!

Re: CIRCLE TANGENT TO THREE LINES??? CANYOU DO IT?

Anonymous — Tue, 25 May 2004 13:02:19 GMT

Does anyone have a solution for a circle tangent to three acrs/circles? Just to two will do too

This is how it is done in AutoCAD

Re: CIRCLE TANGENT TO THREE LINES??? CANYOU DO IT?

Anonymous — Tue, 25 May 2004 14:14:32 GMT

Here are some solutions for two and three circle tangents. (It would be nice to have the geometry methods built-in - something to add to the wish list I guess.)

The methods should be mostly obvious from the figures.

The gray arcs are swung using center and radius with numeric entry using the r > value > + method.

The intersections of the gray arcs are the centers of the tangents to two circles.

The three circle tangent is drawn using the three point geometry method to the centers of the arcs between the two circle tangents (light teal arcs).

OOPS... On closer inspection the three circle tangent is not quite accurate. This will require a little closer study.

Re: CIRCLE TANGENT TO THREE LINES??? CANYOU DO IT?

Anonymous — Wed, 09 Oct 2013 04:52:51 GMT

Almost a decade since this thread was started, and still no Archicad update to extend the options for the circle construction tool.
Here's a video of the technique I just came up with for constructing a circle tangent to three lines. I think it's faster than some of the earlier approaches mentioned.
http://www.youtube.com/watch?v=12TegajqE4E
I hope it helps any future searchers

Re: CIRCLE TANGENT TO THREE LINES??? CANYOU DO IT?

Barry Kelly — Wed, 09 Oct 2013 06:19:07 GMT

I would have just bisected the 2 angles between the 3 lines and the intersection of those bisecting lines is the centre for the circle you need.
Barry.

Re: CIRCLE TANGENT TO THREE LINES??? CANYOU DO IT?

Anonymous — Wed, 09 Oct 2013 06:27:32 GMT

Awesome. Happy to use that, thanks Barry.
Wish you'd weighed in with that sometime in the last nine years, before I made a video
Wonder if I should delete it again? Oh well.

Re: CIRCLE TANGENT TO THREE LINES??? CANYOU DO IT?

Barry Kelly — Wed, 09 Oct 2013 06:50:57 GMT

That was the gist of Laszlo's second post except the 3 lines there formed a triangle.
It even works for his example with the parallel lines.

I liked the video.
It is interesting to see other solutions too.
Barry.

Re: CIRCLE TANGENT TO THREE LINES??? CANYOU DO IT?

Hmooslechner — Sat, 12 Oct 2013 18:31:44 GMT

https://www.dropbox.com/s/yvjz025ril226q1/3Circles1InnerCircleConsstruction.jpg

This should show the only way i found.. its german and my english is too poor to translate it .., but it could show You the way..

Maybe a real mathematic-GDL-Guru could develop such a thiing...

three circles with drifferent radius - 1 inner circle

Hmooslechner — Sat, 12 Oct 2013 18:38:00 GMT

three circles with drifferent radius - 1 inner circle touches each..

This schould be a little work for a real GDL-guru - not me..

Did someone work on this problem?

here the not really simple geometric methode...

https://www.dropbox.com/s/yvjz025ril226q1/3Circles1InnerCircleConsstruction.jpg

There are som other mathematical methodes from Gauss and Descartes which are higher than my mathematic level - so if someone dit it bevore, i easyly could program a graphical user interface...

Re: CIRCLE TANGENT TO THREE LINES??? CANYOU DO IT?

Ben Cohen — Mon, 14 Oct 2013 07:01:54 GMT

Or simply choose the correct construction method and click on the three lines !!

Re: CIRCLE TANGENT TO THREE LINES??? CANYOU DO IT?

Barry Kelly — Mon, 14 Oct 2013 07:25:49 GMT

Show-off!

Funny I always assumed that was tangential to 2 lines then pick a third point.
Just goes to show reading the prompt can help - clearly says pick a third point or tangential line.

Mind you I don't think I have ever needed to use this - that is my excuse.

Barry.

Re: CIRCLE TANGENT TO THREE LINES??? CANYOU DO IT?

Anonymous — Mon, 14 Oct 2013 12:34:26 GMT

Oy vey. I'll get back in my box then.

Re: CIRCLE TANGENT TO THREE LINES??? CANYOU DO IT?

Ben Cohen — Mon, 14 Oct 2013 22:10:27 GMT

hahaha
can't say I have ever need it either.....