Interactive Polygons

Play with a polygon! Try adding or subtracting points.
See the lengths, angles and coordinates, from triangles on up.

images/area-coords.js

Note: due to computer rounding the last digit isn't always accurate

Edit

Use the "Edit" button to manually edit the coordinates, or to enter new coordinates of your own.

Try these quick challenges:

Use ▲▼ to change the number of sides, now drag the points to make a house shape. How many sides do you need?
Make a shape where one corner points inward like a cave
Make two lines cross over each other

What's Regular, Concave, Complex?

Four polygons illustrating regular, irregular, concave, and complex types

When all angles are equal and all sides are equal it is regular, otherwise it is irregular

When any internal angle is greater than 180° (it points inwards) then it is concave. (Think: concave has a "cave" in it), otherwise it is convex.

And a complex polygon intersects itself (the boundary crosses over), otherwise it is simple (like most polygons we deal with). Many rules about polygons don't work when they are complex.