2D and 3D Shapes: Names, Sides and Examples
Shape names for flat and solid shapes: polygons by number of sides, types of triangles, faces, edges and vertices of 3D shapes, and everyday examples.
By Polarzinho ·
Look around: the screen is a rectangle, the ball is a sphere, the stop sign is an octagon and my bamboo is almost a cylinder. Geometry is everywhere, even in a tower of colorful slabs.
Here you get flat shapes, polygon names by number of sides, the types of triangles, 3D shapes with their faces, edges and vertices, and examples you can find at home.
2D shapes and 3D shapes
- 2D (flat) shapes: only width and height, like a drawing on paper. Square, circle, triangle.
- 3D (solid) shapes: width, height and depth, they take up space. Cube, sphere, pyramid.
Common 2D shapes
- Circle: a closed curve, with every point the same distance from the center.
- Triangle: 3 sides.
- Square: 4 equal sides and 4 right angles.
- Rectangle: 4 right angles, with opposite sides equal.
- Rhombus: 4 equal sides, with angles that do not have to be right angles.
- Parallelogram: opposite sides parallel and equal.
- Trapezoid: one pair of parallel sides.
- Oval (ellipse): a "stretched" circle.
Polygon names by number of sides
A polygon is a closed flat shape made only of straight sides. A circle is not a polygon, because it is curved.
- 3 sides: triangle
- 4 sides: quadrilateral
- 5 sides: pentagon
- 6 sides: hexagon
- 7 sides: heptagon
- 8 sides: octagon
- 9 sides: nonagon
- 10 sides: decagon
- 12 sides: dodecagon
Types of triangles
By sides
- Equilateral: 3 equal sides.
- Isosceles: 2 equal sides.
- Scalene: no equal sides.
By angles
- Right: one right angle (90°).
- Acute: 3 angles smaller than 90°.
- Obtuse: one angle bigger than 90°.
The inside angles of any triangle add up to 180°. In quadrilaterals, they add up to 360°.
3D shapes
A face is a flat side, an edge is where two faces meet and a vertex is a corner.
- Cube: 6 faces, 12 edges, 8 vertices. Like a die.
- Rectangular prism: 6 faces, 12 edges, 8 vertices. Like a shoebox.
- Square pyramid: 5 faces, 8 edges, 5 vertices.
- Triangular prism: 5 faces, 9 edges, 6 vertices.
Round 3D shapes
- Sphere: like a ball.
- Cylinder: like a can.
- Cone: like an ice cream cone.
Geometry in Trimora
In Trimora you stack slabs that slide over the tower. Each slab is a rectangular prism. When it lands off center, the part hanging over the edge is cut off and the rectangle on top gets narrower.
PolarzinhoMissed the center, lost a strip. The rectangle shrank, and so did my pride.
Land it right in the center and nothing is lost. And the tower keeps climbing, floor by floor.
FAQ
What are the basic shapes?
Circle, triangle, square and rectangle.
What is a 6-sided shape called?
A hexagon.
How many faces does a cube have?
6 faces, 12 edges and 8 vertices.
Is a circle a polygon?
No, because polygons only have straight sides.
Your turn
Find at home: a cylinder, a cube and a rectangle. Bonus: count the edges of a shoebox.