The objects around us come in various shapes and sizes. In general, we can see shapes such as triangles, squares, and circles everywhere around us. Moreover, shapes such as a sheet of paper, have only length and breadth. Thus such shapes are 2D or two-dimensional. While other shapes such as the shape of a house, have length, breadth, and height. Thus such shapes are 3D or three-dimensional. Let’s learn more about 2D and 3D shapes!
In geometry, a shape or a figure that has a length and a breadth is a 2D shape. In other words, a plane object that has only length and breadth is 2 dimensional. Straight or curved lines make up the sides of this shape. Also, these figures can have any number of sides. In general, plane figures made of lines are known as polygons. For example, triangles and squares are polygons.
Because 2D objects have no depth, they cannot be physically held; a 2D shape is absolutely flat. Plane shapes are another term for 2D shapes: a two-dimensional, closed, or flat plane shape. A sheet of paper, for example, has a two-dimensional shape. It has two dimensions: length and breadth, but no depth or height.
Examples of 2D shapes
Rectangle, circle, square, triangle, quadrilateral and pentagon are some examples of 2D shapes.
Types of 2D Shapes
2D shapes are further classified into 2 types – regular or irregular – based on their length and interior angles.
A 2D shape is considered to be regular if all of its sides have the same length and all of its interior angles are of the same measurement.
A 2D shape is irregular if all of its sides are unequal in length and all of its angles are unequal in measurement.
2D Shapes types
Properties of 2D Shapes
Regular and irregular 2D shapes include the circle, triangle, square, rectangle, pentagon, and hexagon. Let us look at a few of them and their properties.
Circles are entirely round shapes formed by a single curved line. The curved line’s points are at equal distances from its centre.
A semi-circle has two sides, one curved and one straight. The entire arc has a 180° angle.
Triangles (3 sides) –
A triangle is a closed polygon with three sides, three vertices, and three angles. The sum of the triangle’s three interior angles is 180°.
An equilateral triangle is a regular triangle with 60° angles each.
Any triangle with one right angle is referred to as a right-angled triangle.
A scalene triangle is an irregular triangle wherein every side and angle is unique.
An isosceles triangle has two equal sides and two equal angles.
Quadrilaterals (4 sides) –
A square is a regular quadrilateral with all vertices at 90° angles.
A kite has two sets of equal-length sides, with diagonals intersecting at right angles.
A rectangle is made up of two parallel straight lines, each with a 90° angle.
A rhombus is defined by two parallel lines, equal sides, and opposite equal angles.
A trapezium has one parallel pair of lines.
A parallelogram is made up of two parallel lines and two opposite equal angles.
Polygons (4+ sides) –
A 5-sided shape is called a Pentagon. Interior angles add up to 540°.
A 6-sided shape is called a Hexagon. Interior angles add up to 720°.
A 7-sided shape is called a Heptagon or Septagon. Interior angles add up to 900°.
An 8-sided shape is called an Octagon. Interior angles add up to 1080°.
A 9-sided shape is called a Nonagon. Interior angles add up to 1260°.
A 10-sided shape is called a Decagon. Interior angles add up to 1440°.
A three-dimensional shape is defined in geometry as a solid figure or an item or shape with three dimensions — length, breadth, and height. In our day to day life, we see several objects around us which have different shapes. For example, books, balls, ice-cream cones etc. One thing common in these objects is that they all have some length, breadth and height or depth. Thus they have three dimensions and so are known as 3D shapes. The D in 3D stands for dimensional. 3D shapes occupy space. In a world with three dimensions, you can travel forward, backward, right, left, and even up and down.
Examples of 3D Shapes
Cuboid, cube, cylinder, sphere, pyramid and cone are a few examples of 3D shapes
Understand the concept of Polyhedron here in detail.
Types of 3D Shapes
In mathematics and real life, there are many 3D shapes and objects with different bases, surface areas and volumes. Let us look at a few of the most commonly seen 3D shapes.
A sphere is round and circular in shape. All the points on the surface of the sphere are equidistant from the centre. It has the following dimensions: radius, diameter, circumference, volume, and surface area. There is only one face, no edges, and no vertices. For example, a ball, lemon, etc.
Cube and Cuboid
The cube and cuboid have the same number of faces, vertices, and edges. The major distinction between a cube and a cuboid is that a cube has all six faces that are squares, whereas a cuboid has all six faces that are rectangles. For example, ice cube, Rubik’s cube, etc.
A cylinder is a three-dimensional shape with two round faces, one at the top and one at the bottom, as well as one curving surface. A cylinder has a radius and a height. It is a 3D object with two identical round or oval ends. For example, candles, batteries, cans, etc.
A cone has a flat (circle-shaped) base and a pointy tip at the top. The pointy end at the top of the cone is referred to as the ‘Apex.’ A cone has a curved surface as well. For example, ice-cream cone, party hat, Christmas tree, etc.
A torus, often known as an O ring, is a doughnut-shaped object. It is created by spinning a smaller circle with a smaller radius (r) around a larger circle with a larger radius (R). For example, tire, ring, doughnut, etc.
A pyramid has a polygon base and an apex with straight sharp edges and flat faces. Types of pyramids –
Tetrahedron – Pyramid with a triangular base
Square Pyramid – Pyramid with a quadrilateral base
Pentagonal Pyramid – Pyramid with a pentagon as base
Hexagonal Pyramid – Pyramid with a hexagon as base
Octagonal Pyramid – Pyramid with an octagon as base
A prism is a 3D form that consists of two similar shapes that face each other. Prisms are classified into several types, including triangular prisms, square prisms, pentagonal prisms, hexagonal prisms, and so on.
A three-dimensional form having flat polygonal faces, straight edges, and sharp corners or vertices is known as a polyhedron. Polyhedrons are further classified into Prisms, Pyramids and Platonic Solids (Eg. Octahedron, Dodecahedron, Icosahedron).