Shapes with Straight Sides and Perfect Curves

Now let's look at shapes! Geometric shapes come in many varieties, but two big categories are polygons and circles.

Polygons

A polygon is a closed shape with straight sides. The simplest polygon is a triangle (3 sides), but polygons can have many sides, like pentagons (5), hexagons (6), and so on.

Properties of Polygons

• Sides: The straight lines that make the shape.
• Vertices: The corners where sides meet.
• Regular vs. Irregular: Regular polygons have all sides and angles equal.

Circles

A circle is a perfectly round shape where every point is the same distance from the center. This distance is called the radius.

• Diameter: A line that passes through the center, twice the radius.
• Circumference: The distance all the way around the circle.

Fun Fact

The ratio of the circumference to the diameter is always \( \pi \) (about 3.14).

Everyday Uses

Polygons are everywhere: in stop signs (octagons), honeycombs (hexagons), and art. Circles show up in wheels, clocks, and pizzas!