2D Shapes
by Vera, Aug 01 2023
2D Shapes
Have you ever noticed the difference between the shape of a credit card and a box, or a thin crust pizza and a football? The key disparity lies in their width. Objects like credit cards and thin-crust pizzas are what we call 2D shapes, meaning they are flat and can be represented on a piece of paper or a flat surface. On the other hand, objects like boxes and footballs are not flat and belong to the category of 3D shapes.
What is 2D Shapes
2D shapes are flat figures that have length and breadth but no thickness. Imagine drawing on a piece of paper - whatever you create, like a circle or a square, are 2D shapes. They don't have any thickness to them. Things like plates, cards, sheets, clocks, and windows are examples of 2D shapes that we see in everyday life.
2D Shapes vs. 3D Shapes
Shapes can be put into two groups: 2D and 3D. The "2D" means "2-dimensional," and it refers to flat shapes like the ones we draw on paper. They need two coordinates to say where their points are. On the other hand, "3D" means "3-dimensional," and these shapes have more depth, like the objects we can touch, such as a box or a ball. They need three coordinates to describe where their points are.
2D Shape Examples and Brief Properties
Curved Shapes:
- Circle: A circle is perfectly round, and all points on its edge are the same distance from its center. You can describe it using its radius (from the center to any point on the edge) and diameter (twice the radius).
- Ellipse: An ellipse looks like a stretched circle with two different lengths - major and minor. The distances from any point on the ellipse to its two foci add up to a constant value.
Polygons:
- Triangle: Triangles have three straight sides, and the angles inside them add up to 180 degrees. Some common types are equilateral (all sides and angles are equal), isosceles (two sides and angles are equal), and scalene (all sides and angles are different).
- Quadrilateral: These shapes have four straight sides, and the angles inside them add up to 360 degrees. You might have heard of a square (all sides and angles are equal) and a rectangle (opposite sides equal, right angles).
- Pentagon, Hexagon, and more: These are 5-sided, 6-sided, and other-sided shapes, respectively. Some regular ones have all sides and angles equal.
Properties of 2D Shapes
- Perimeter: The perimeter is the total length around a 2D shape.
- Area: The area is the space inside a 2D shape.
- Symmetry: Some 2D shapes have a line of reflection that divides them into two equal halves.
- Angles: 2D shapes have angles formed by their sides, like right angles (90 degrees), acute angles (less than 90 degrees), obtuse angles (more than 90 degrees), or straight angles (180 degrees).
- Diagonals: In some shapes, like polygons, you can draw lines connecting non-adjacent corners, creating diagonals that split the shape into smaller parts.
Understanding 2D shapes and their properties helps us identify different geometric figures in our world. From simple circles to complex polygons, these shapes play an essential role in math and our daily lives. So the next time you see a credit card or draw a square, you'll know more about the amazing world of 2D shapes!