definition of polygon shapes

What Is a Polygon?

A polygon is a closed 2D shape made of straight lines connected at their endpoints. Think triangles, squares, and beyond. They've got sides (the lines), vertices (the corners), and angles both inside and out. Some are regular with equal sides, others irregular. They're either convex (all angles less than 180°) or concave (at least one angle over 180°). The math is neat – interior angles always sum to (n-2) × 180°. Architects and honeybees know their value.

multi sided geometric shape

Shapes. They're everywhere around us. From the triangular yield signs on the road to the octagonal stop signs that make you late for work. But not just any shapes—polygons. These aren't your free-form, curvy doodles. Polygons play by strict rules.

A polygon is a closed two-dimensional shape formed entirely of straight line segments. These segments connect at their endpoints, creating a figure that has at least three sides and angles. No curves allowed. Period. Think of it as the geometric equivalent of "no shirts, no shoes, no service." Straight lines only, or you're not getting in the polygon club.

The anatomy of a polygon is pretty straightforward. Sides are the straight line segments that form the boundary. Vertices (fancy word for corners) are where these sides meet. Interior angles form inside the shape, while exterior angles point outward. Diagonals? Those are line segments connecting non-adjacent vertices. Nothing complicated. Just lines connecting points.

Polygons come in different flavors. Simple polygons keep their sides from crossing each other. Complex ones? They're messy—sides intersect like family drama at Thanksgiving dinner. Regular polygons are the perfectionists of the group, with all sides and angles equal. Irregular polygons don't bother with such uniformity.

Polygons: some play by the rules, others create chaos. Like families, some stay in line while others embrace the drama.

Then there's convex polygons, where all interior angles are less than 180 degrees. They never cave inward. Ever. Concave polygons, on the other hand, have at least one interior angle exceeding 180 degrees and require at least four sides to form.

The classification system is based on the number of sides. Three sides? That's a triangle. Four makes a quadrilateral. Five gets you a pentagon. Six, a hexagon. Eight, an octagon. Polygons with n vertices and sides are technically referred to as n-gons in mathematical terminology. And yes, there are names for polygons with hundreds of sides, but nobody has time for that.

Mathematics gives polygons some interesting properties. The sum of interior angles follows a simple formula: (n-2) × 180°, where n is the number of sides. Exterior angles always add up to 360°. Always. The number of possible diagonals? That's n(n-3)/2. The perimeter is just the sum of all sides. Area calculations vary by type, because nothing can be that simple.

In the real world, polygons are workhorses. Architects use them in building designs. Engineers rely on them for structural elements. Nature forms honeycombs and snowflakes as polygons. Artists create geometric patterns with them. That tile floor in your bathroom? Polygons.

Mathematically speaking, polygons are fundamental. They form the basis of geometry, show up in trigonometry, and are essential for coordinate systems. Computer graphics? Couldn't exist without polygons. Every 3D video game you've played is just a bunch of polygons working together. They're simple but powerful. Like duct tape, but for math.

Frequently Asked Questions

Are All Polygons Flat or Can They Exist in 3D Space?

Polygons are traditionally defined as flat, 2D shapes. Period.

But they absolutely can exist in 3D space. When polygons form the faces of polyhedra like cubes or dodecahedrons, they're still flat but positioned in three dimensions.

There's also such a thing as "skew polygons" – non-planar polygons whose vertices don't all lie in the same plane.

Pretty wild stuff, actually.

How Do Polygons Relate to Everyday Objects and Architecture?

Polygons are everywhere. Your home is full of them—rectangular TVs, hexagonal tiles in bathrooms, octagonal clocks on walls.

They're practical building blocks of our world. Architecture leverages their properties relentlessly: triangular roof trusses for strength, hexagonal patterns for efficient space usage.

Nature got there first, though. Honeycomb cells? Perfect hexagons. Snowflakes? Six-sided wonders.

Even pizza slices—triangles that lead straight to your mouth.

Can a Polygon Have Curved Sides?

No, a polygon cannot have curved sides. Period. By definition, polygons consist exclusively of straight line segments connected end-to-end. That's their whole deal.

Circles, ovals, and other curvy shapes? Not polygons. They're called curvilinear figures instead.

Some people try to blur the lines, combining straight and curved sides into one shape. Nice try. Still not a polygon.

The rule is simple: if it's curved, it's out.

What's the Difference Between Regular and Irregular Polygons?

Regular and irregular polygons? Night and day.

Regular ones flaunt equal sides and angles. Perfect symmetry. Think of a square or equilateral triangle—boring but precise.

Irregular polygons? Wild cards. Different side lengths, varied angles. They're everywhere in nature, while their regular counterparts dominate architecture and design.

One's uniform, the other's chaotic.

One fits perfectly in a circle, the other doesn't even try.

How Are Polygons Used in Computer Graphics and Game Design?

Polygons form the backbone of 3D graphics.

They're basically flat shapes—triangles, quadrilaterals—that connect to create complex objects. Game designers juggle polygon counts constantly.

Too many? Game runs like molasses.

Too few? Characters look like they're from 1995.

Modern techniques like normal mapping create the illusion of detail without the performance hit.

Every object you see in games—characters, buildings, terrain—they're all constructed from these simple geometric building blocks.