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### Convex and Concave Polygons

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Date: 3/23/96 at 2:17:26
From: Anonymous
Subject: convex and concave polygons

What are convex and concave polygons?

Thanks,
```

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Date: 3/30/96 at 3:46:1
From: Doctor Jodi
Subject: Re: convex and concave polygons

Hi there!

Probably most of the polygons you know are convex.  They're
the ones that geometry classes usually talk about.  Squares,
trapezoids, rhombuses, rectangles, triangles are all convex,
because any line you draw from one vertice to another in the
polygon is on a side or inside the polygon.

A concave polygon is one that is "caved in" a little bit.  This is
NOT a very good drawing, but maybe it will help a bit

*/////////*
|         /
|        /
|       *
|        \
*/////////*

See the *'s?  Those are supposed to be the vertices.  You can see
on the left side that the two vertices are connected by a side, just
as they would be in a convex polygon.  But on the other side, you
can connect two of the vertices in a line OUTSIDE the polygon.
That makes this polygon concave.

I hope this makes sense.  Write back if you have other questions!

-Doctor Jodi,  The Math Forum

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Associated Topics:
Middle School Definitions
Middle School Geometry
Middle School Triangles and Other Polygons

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