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A problem that I do not know how to solve.


prax3des

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Hi, I have the following issue.

I have a Point (A) that can be moved by Line 1 and Line 2

I have a Point (B) that can be moved only by Line 3

I have a Point C that can be moved only by Line 4

The lengths LC (25) and LD (15) form 40 which is a length to be respected.

The length LA is variable.

How can it be done to align Points (A), (B) and © so that they respect the comments?

I give examples of how the cases of solution should be.

 

Thank you.

Problem.dwg

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You have to decide which point is to be fixed - A, B or C? Because fixing any one of them decides the positions of the other two.

 

Have you tried using constraints?

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No, that is the problem.

Point (A) can be aligned with Line 1 or Line 2

Point (B) Aligned with Line 3

Point © Aligned with Line 4

Therefore if Point (A) is at the midpoint of Line 1, if Point (B) aligned with Line 3 and Point © aligned with Line 4, we would know the Length of LA.

 

 

Is very difficult for me:(

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There is no single solution as you have already shown, therefore to get one answer you MUST fix one point.

 

Or do you want a general equation to satisfy conditions? That is perhaps beyond the scope of AutoCAD, unless you go parametric.

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This picture shows the range of solutions possible. I have drawn the extreme positions and some intermediate ones.

So for each particular value of one of the points (A, B or C) there is a unique value for the others.

Range of solutions.PNG

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correct !!

Therefore I look for the method that marking a point, for example (A) at a distance X, Y of Line 1 and Line 2 would give me as solution the points B and C

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So you are fixing point A.

As I said in my first response, use constraints. That would seem to be the solution unless you go for trial and error!

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No, that is the problem.

Point (A) can be aligned with Line 1 or Line 2

Point (B) Aligned with Line 3

Point © Aligned with Line 4

Therefore if Point (A) is at the midpoint of Line 1, if Point (B) aligned with Line 3 and Point © aligned with Line 4, we would know the Length of LA.

 

 

Is very difficult for me:(

 

From your example it look like the diagonal line is required to be perpendicular to line B C.

Using constraints you can set this up so if you move A, B, or C they will adjust to keep your parameters in check.

 

Lines 1 and 4 will be set to vertical and Fixed in place.

Lines 2 and 3 will be set to horizontal and Fixed in place.

Point A would be COINCIDENT to line 1 (or COINCIDENT to line 2 in another setup)

Point B would be COINCIDENT to line 3

Point C would be COINCIDENT to line 4

Line C-D would have a dimconstraint to 15 (and again to 40 in another setup)

Line B-D would have a dimconstraint to 40 (and again to 15 in another setup)

Now you can grab the grip of the end points of line A-D or B-C and adjust.

 

You will have to end up with 4 different solutions with the various parameters.

Edited by rkent
coincident not collinear
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