Geometric shapes make up just about everything, from flat squares on your checkerboard to the cuboid shapes of the buildings all around. The study of geometry covers these shapes, but sometimes more info is needed than what you learn in class. Keep reading for a breakdown of over 20 shapes and a list of different geometric shapes.
What Are Geometric Shapes?
Perhaps the easiest way to learn what a geometric shape is would be to think of a non-geometric shape. Pebbles, leaves, clouds, all of those are inconsistent in shape and difficult to measure the area of. Geometric shapes are figures that have a defined formula for creating them and finding their area. They have specific lines, curves, and points that make them up and help us know what they are.
2D Geometric Shapes
This is everything that we draw. 2D (or 2-dimensional) uses only length and width and is flat like a piece of paper. We all learned triangles, squares, and circles as grade schoolers – but these basic shapes get a tad bit more difficult.
Three-Sided Shape: Triangles
Three sides, three angles, and three vertices (points). These are what make up a triangle. There is more than one way to describe and define a triangle, though.
By Angle
The three lines used to make up a triangle can come in many lengths and be positioned in 3 distinct ways to create different angles (remember, one of the characteristics of triangles are its three sides!). If you add the three angles of a triangle, it must add up to 180 degrees.
- Right-angled triangle: A right triangle is where one angle of the triangle is 90 degrees (a right angle) exactly.
- Acute-angled triangle: If all angles are less than 90 degrees, you have yourself an acute triangle.
- Obtuse-angled triangle: Obtuse triangles contain one angle that is over 90 degrees.
By Sides
There are also three types of triangles based on the sides!
- Equilateral Triangle: If all sides are the same length, it is an equilateral triangle.
- Isosceles Triangle: If only two sides are the same length, it’s isosceles.
- Scalene Triangle: If no sides are the same length, then it’s a scalene triangle.
Four-sided Shape: Quadrilaterals
We’re moving out of the threes and into the fours! Quad in quadrilaterals means four, and that’s what these geometric shapes are all about. Lucky for you, there are way more than four ways to define these types of shapes.
Rhombus
A rhombus features four equal sides, and each opposing side is parallel. “Doesn’t that make it a square?” Technically, it can. A square needs all right angles, whereas a rhombus does not. However, all squares are rhombuses, but not all rhombuses are squares.
Rectangle
With a rectangle, you have four sides where opposing sides are equal and parallel. A rectangle also requires that all angles be 90 degrees (aka right angles). Since a square also fits these rules, all squares are rectangles! Not all rectangles are squares, though, because all four sides don’t need to be equal, just the two opposite of each other.
Square
You probably have a clear idea of what this is based on the last two. Unlike a rectangle, a square’s sides are equal in length, which means its angles are 90 degrees.
Parallelogram
Now, what geometric shape if the opposite sides are equal and parallel? That makes it a parallelogram. This means each of the three listed above falls into this sub-category.
Trapezium
With a trapezium, you only have a pair of parallel sides, which are known as bases. The other two are called legs.
More Than Four Sides
Once you get over four sides, the names of these shapes start just defining the number of sides and not so much how they are laid out.
Pentagon
“Penta” is five in Greek, meaning this is a shape with five sides and five angles. There are four types of pentagons: regular, irregular, convex, and concave.
Hexagon
Moving up a side, we have the hexagon, which has six sides and six angles. Like pentagons, hexagons have four types.
Octagon
The octagon, much like the octopus, is all about the number 8. This means you have eight sides and eight points.
Nonagon
If you add another side to an octagon, you will get a nonagon, a geometric shape with nine sides and nine points. Unlike the pentagon and hexagon, a nonagon has six types – regular, irregular, convex, concave, simple, and complex.
Decagon
Coming in at ten sides and ten points, we have the decagon! The same categories used to define a nonagon are also used for this geometric shape.
Curve 2D Shapes
We’ve covered most of the shapes with all straight sides, and now it’s time to throw a curve ball at you (get it?). There are two types of curved 2D shapes: those with no straight line and those with a straight line.
Circle
A circle, the most famous curved 2D shape, has no edges or corners. A circle also has a radius, which is the center.
Ellipse
An ellipse is another completely round shape; however, this one has two focal points. Think of it as a perfectly symmetrical oval. “Why not just call it an oval?” you ask. Well, the only definition of an oval is that it is egg-shaped!
Sectors
Sectors are portions of a circle. They contain part of the arc and two lines connecting to the center point. A slice of pizza is a sector.
Parabola
Think of a cone; now, think of slicing through the side of the cone and out the flat bottom. This is where the parabola shape comes from. It contains one curved section connected with a straight line.
Hyperbola
A hyperbola is the same but with a steeper cut. If the cone was standing upright, this would be like if you sliced straight down the side and out the bottom.
Three-Dimensional Shapes
Now that we’ve established what some geometric shapes look like on paper let’s move into the physical world. 3-D shapes take up space, like a soccer ball or the Great Pyramids.
Sphere
A sphere is the only 3D shape with no straight edges. It is a purely curved solid shape, like a ball or an apple.
Cube
A cube is a six-sided 3D shape in which all sides are squares of equal size.
Cuboid
Similar to a cube, a cuboid is also a six-sided shape. However, not all sides have to be squares. If you can measure its height, length, and width using straight lines, it is a cuboid.
Cone
To identify a cone, you should remember only two things – it only has one circular face, and it doesn’t have an edge or vertex. The flat face has a curved surface which goes up into the vertex. Fun fact: cone comes from the Greek word “konos,” meaning wedge or peak.
Cylinder
When you fold a rectangle along its length and then close both openings, you create a cylinder. These can be set flat on either their base or top or rolled when placed on their sides. The Pringles can is a well-known cylinder.
Triangular Prism
The triangular prism has two triangle bases connected with three rectangular sides. An A-frame house is a perfect example of this shape.
Hexagonal Prism
Where a triangular prism has two triangle bases, a hexagonal prism has two hexagon bases. These are connected with six rectangle sides. This might seem like a super unique shape, but we bet you use it every day to take notes! The unsharpened pencil is a good example of a hexagonal prism.
