cancel
Showing results for
Did you mean:
cancel
Showing results for
Did you mean:

SOLVED
Highlighted
Newbie

## Iregular polygon-area

Hi,

How can I determine the area and center of mass of a polygon knowing the coordinates of its points? the lenght of the segment 01 and the angle between lines 05 and 45?

Thank you,

Gabriel

Tags (2)
1 ACCEPTED SOLUTION

Accepted Solutions

## Re: Iregular polygon-area

For whatever it may be worth, here is a much more compact version of the intersect() routine. One of those "why didn't I thought of that before" things.

33 REPLIES 33

Here's one way:

## Re: Iregular polygon-area

Here's another way.

Alan

## Re: Iregular polygon-area

May I join the session?

Here is a third way 😉

## Re: Iregular polygon-area

Well done Werner. Fred and I both forgot about the CofG part!

Alan

## Re: Iregular polygon-area

 Well done Werner. Fred and I both forgot about the CofG part!

Looks like we all forgot about the second question

 the lenght of the segment 01 and the angle between lines 05 and 45?

but I am not quite sure about this question, especially as the first part seems too trivial.

## Re: Iregular polygon-area

Thank you gentlemen,

I'm not a regular matchad user, but whenever I search on this forum I see solutions from some of you guys. Thank you for sharing your experiece with us!

Werner, the angle was part of a second questions. It will follow. Now I have to run to a meeting.

regards,

Gabriel

## Re: Iregular polygon-area

I tried, without any success, to extend the solutions proposed so that I can account for the variability of the angle alfa. I inserted an explanatory figure at the end of the worksheet. If alfa is 0 line 05 is horizontal. The top limit of alfa is defined by joining points 4 and 5. I would like to define alfa as a incremental variable within these limits. Line 45 has fixed slope (beta angle).

The idea is to make point 5 run on the 45 line and consequently generate values of the area and center of gravity for a fixed increment of alfa.

E.g. if alfa ranges between 0 and 10 deg, I would like to calculate for each degree of alfa the area and center of mass.

Thank you for all your good input.

Greetings,

Gabriel

## Re: Iregular polygon-area

With thanks to Werner for doing the hard work:

## Re: Iregular polygon-area

Its not fully clear from your description - do you want the line 45 run through the point (L/0) or do you want that the angle 054 at the variable point 5 to be a given value beta?

I guess its the first scenario and L should be the sum of L1 to L4 (divided by x.scale) and the angle at point 5 will vary.

In the second case point 5 would move on a circle and L.4 would be obsolete, so I guess this is not what you are supposed to do.