topic Re: Drawing Tangent Lines in Documentation

Drawing Tangent Lines

Anonymous — Wed, 31 May 2023 08:18:52 GMT

I've hit upon an annoying defficiency in ArchiCAD, again, and I'm wondering if anybody out there has a solution (aka: workaround).

How do you draw a line that's tangent to two circles? I have a site plan with property lines at some odd angles which are not dimensioned. All I have to go on is some dimensions that locate the corner of the building. Going the reverse route, I need to ... [long story short] ... draw a line that's tangent to 2 circles.

I've tried two different ways of constructing the tangent line geometrically, but the solution always ends up being "slighly" off (depending on the scale. For a site plan you're talking feet - a considerable problem).

So does anybody have any suggestions?

Thanks in advance.

Re: Drawing Tangent Lines

Anonymous — Sat, 05 Jun 2004 01:56:51 GMT

Sergio,
Do a search on Archicad-Talk, keyword tangent.
There has been considerable discussion on this issue.
Peter Devlin

Re: Drawing Tangent Lines

Anonymous — Sat, 05 Jun 2004 15:53:58 GMT

Here it is

Re: Drawing Tangent Lines

Djordje — Sun, 06 Jun 2004 18:24:41 GMT

Sergio wrote:
How do you draw a line that's tangent to two circles?

http://archicad-talk.graphisoft.com/viewtopic.php?t=485

http://archicad-talk.graphisoft.com/viewtopic.php?p=2456#2456

HTH,

.

Steve Jepson — Mon, 07 Jun 2004 03:20:41 GMT

Deleted

Re: Drawing Tangent Lines

Anonymous — Mon, 07 Jun 2004 14:41:02 GMT

Adalbert wrote:
Here it is

Oh wow, finally a method that works. Thank you very much Adalbert. Maybe this one should be posted in the tips 'n tricks section as the only accurate and simple working way of drawing tangents (to 2 circles or between a point and a circle), or until GS decides to help us out with a tangent command. Like I said before, none of the other ways of constructing a tangent were accurate to me, and I'd seen and tried them before (thank you anyway guys).

However, I would think that a tangent command should be standard in any CAD software. Maybe I'm asking for too much since I don't need this EVERY day, but...

The only additional explanation/clarification I'd like to make is that if the circles intersect each other, you need to scale them down appropiately so you can use this method.

Re: Drawing Tangent Lines

Laszlo Nagy — Tue, 08 Jun 2004 07:20:45 GMT

This is also accurate:
http://archicad-talk.graphisoft.com/viewtopic.php?p=15166&highlight=tangent#15166
Laszlo

Re: Drawing Tangent Lines

Anonymous — Tue, 08 Jun 2004 08:42:09 GMT

Could be accurate, but it seems to involve more drafting (you have to know the radius of one, subtract the radius of the other, etc). I don't remember if I've tried it out or not - if I did, I either messed up or... ?

But thanks for pointing that out. It's good to see people listen (and help)...