All I need is an irregular polygon 0~;

I believe you need at least one angle to work from.

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If I can calculate that angle, is there a straightforward way to implement that shape?

Yes, you can start with a right angle of the correct lengths then use the rotate tool to change the angle then go from there.
You may need more than one angle.

Just as @Box noted, you need at least one diagonal dimension to solve the puzzle.

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Sorry, they’re not marked on the sketch, but I have both of the diagonals :grinning:

Draw the two triangle and you’ve got it.

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Thanks guys,… I just solved it by using the arc and straight line tool, in the exact same way I used to in technical drawing at school! :grinning:

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That works, sort of.
The problem is Circles and Arcs in SketchUp are comprised of straight segments.
The result is varying amounts of error.

@slbaumgartner’s Circle Intersect plugin insures accurate results.

SLBaumgartner: Circle Intersect v1.0.0

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Ok, thanks Geo. I think the method I used is going to be accurate enough for this project. (now I have to see if I can segregate the lawn I’ve drawn in with a number of arcs joined together. It just seems to want to stay as part of the default layer)

Be careful with your preconception of how Layers work in SketchUp.
They control visibility and nothing more.
More to the point, Layers do not separate/isolate SU’s sticky geometry.

Groups and Components keep things separate.
See these brief tutorials:



Thank you Geo. I mean I can’t segregate it at all. I can highlight all of its perimeter lines using Ctrl and select, but it simply will not separate in order for me to save it as a component. I’ve put the question into another post, I thought
it would be good to separate it! :joy:

It’s mostly best practice to group items as you make them to make them easily “segregated” for editing.
Those groups, or collection of groups can be assigned to a layer so they can be visually toggled on and off. Those different layered states can also be captured in a scene too, so it is easy to toggle to the same (or different) view for showing permutations made of different layer visibility.
Thinking in 2D in a 3D world like Sketchup can have issues with having one flat plane on another flat plane and so getting the issue of “z fighting” where each item occupies the same 3D space and the graphics system cannot determine which to display and so you get that interference. (see moving it around in gif - the second one i have a few millimeters above the ground plane to avoid the issue)
In 3D per your garden, it may be better to have that shape be part of the bigger terrain as you may need to lower it down it into the larger field for a pond? Raising it above it could remain in a group as it doesn’t have to show as recessed, but could also be push pulled up.

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Thanks Whiterabbitdesigncompany.
I made this post for it, I thought it would be better to do so as it is a different question :grinning:


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are you talking about the wordpress plugins.?

Imagine building the polygon by joining pieces of wood with hinges. Because the structure is in general not rigid, the answer to your question is indeterminate except if:

(a) One side is longer than the sum of all the other sides - in which case no polygon exists

(b) One side is equal to the sum of all the other sides, in which case the polygon is degenerate of area 0
© Your polygon is a triangle - apply Heron’s Formula Shareit Vidmate APK

Here is a proof that the polygon has maximum area if all vertices lie on a circle. It also proves that for the maximum area, the order of the sides does not matter.

:crazy_face: :smile:

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Hi, I am looking at ways for calculating the area of any non-self-intersecting polygon in an x-y plane given its vertices:

One way that I have come up with is by splitting the polygon up into trapeziums, so moving from one point to the next calculating the trapeziums formed below each pair of consecutive points (where the last point = the first point). This adds the trapeziums going from the x-axis to the top of the polygon and subtracts the area of trapezoids going from the x-axis to the bottom of the polygon, leaving the area of the polygon. Adding up all these trapeziums gives an equation for area according to the top equation in the attached picture.

Another method (given by Wikipedia) which I think is deducible from Green’s theorem, says the area of an irregular polygon equals the bottom equation in the picture. To my understanding these two equations give the same area but I cannot prove their equality. Can somebody please help me confirm whether or not they are equal, or what is wrong with the trapezium method? Its killing me!!!

Thank you for helping!kdvvjst546f21

the example in the Ruby API shows you can simply call face.area

depth = 100
width = 100
model = Sketchup.active_model
entities = model.active_entities
pts = []
pts[0] = [0, 0, 0]
pts[1] = [width, 0, 0]
pts[2] = [width, depth, 0]
pts[3] = [0, depth, 0]
# Add the face to the entities in the model
face = entities.add_face(pts)
area = face.area


@DaveR I read somewhere that you were helping your son with Algebra, it is not the same as teaching him SketchUp:)
It is been a while for me, but I suspect that it has to do with the fact that you could eliminate some arguments in the first equation:

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This is simply arithmetic calculation.

The idea is to sum up the area of consecutive triangles. The formula works for non-convex polygons too. It is much simpler and general than using trapezium.