I work with rhino in long time but I’m beginner in kangaroo.
Now I’m testing bouncy solver to get boundary (curve X) that reduced by building coverage ratio.

Curve X : polyline with 6 vertices, area is 276

Point A, B : anchored Point

Polygon Area : reduced Area (276*0.7=193)

Point on Mesh : point on inside curve

Angle A: anchored Angle A

Angle B:anchored Angle B

Running Solver, it didnt work in my expectation.
1,2,3,4 are work but 5,6 are didnt
and
The Curve which is Output of Solver, make unintended intersection.

Can you help me any point?
I attached Rhino and GH files. and 4 images of them.
I think This is beginners question, please guide me.

thank you for reading.
and Is there any manual for Kangaroo website for beginner?

The PolygonArea goal adjusts the positions of the polygon’s vertices to try and achieve the target area.
It does not ever add or remove vertices or sides.
Your input curve has 4 sides, while the green shape labelled ‘My Expectation’ has 6 sides.
If you start from a 6 sided shape, you should be able to get the result you want.

Actually, Curve X has 6 vertices (including point A and B) and 6 sides
I knew that PolygonArea goal does not add or remove vertices. That’s why I wondering about the converged Polyline.

And, this topic is trying to make some 2d drawing just like your Clip on Vimeo 6 years ago.
It’s 3minutes clip that introducing about New Solver. it starts with 2d drawing of red lines, moving point or line with Grab that I want to trying to make.
If you don’t mind, Can you tell me about somthing that you post, write or upload about that kind of Solver?

I had another look and spotted a few things-
The PolygonArea goal currently requires that the polygon has its points oriented counter-clockwise.
In a future release I should at least add a note on the input, or make it so that they are flipped automatically.

Also the angles were measured the opposite way around. This is how the angles are measured:

With these things changed it works: Area_fix.gh (22.8 KB)

@DanielPiker It’s nice and kind solution.
Now I can understand (a little) that how angle works. and It needs another goal such as End point.
I have a lot of things to ask, but I keep in mind for a next time.
Thank you, I really appreciate that.