In geometry, shapes are the form of defining and determining objects. A shape is defined for an object or any external surface or boundary, apart from other properties such as colour or material type. For example, a blue ball, made up of rubber materials is round in shape. In the same way, there are various geometric shapes we see in our day to day life.

The shapes are determined by their dimensions. Based on dimension, there are two-dimensional shapes and three-dimensional shapes. The names of basic 2d shapes are circle, triangle, square, rectangle, and basic 3d shapes are sphere, cube, cone, cylinder, etc. Some of the real life examples are: a rectangular plot, a circular ground, sugar cube, gas cylinder, ice-cream cone, etc.

## Types of Shapes

It is not necessary that shapes have to be regular like circle, square, cube, cylinder, etc. Shapes are also classified as regular or irregular and concave or convex.

Regular shapes have uniform size. It means their dimensions are uniformly distributed. For example, a regular pentagon. But irregular shapes are not uniformly distributed in the XY plane.

Also, there is a huge category of some simple shapes. For example, a polygon, which is a closed shape, can be categorized into different figures based on the number of sides. A polygon is made up of line segments that are joined together end to end.

### Polygons – Based on Sides

Types of polygon are:

- Triangles (3 sided polygon)
- Quadrilaterals (4 sided polygon)
- Pentagon (5 sided polygon)
- Hexagon (6 sided polygon)
- Heptagon (7 sided polygon)
- Octagon (8 sided polygon)
- Nonagon (9 sided polygon)
- Decagon (10 sided polygon)

### Polygons – Based on Regularity

- A regular polygon has all its sides equal in length and all its angles equal in measure.
- An irregular polygon does not have all the sides equal in length and angles are also not equal in measure.

### Concave and Convex Polygon

- A convex polygon has all its interior angles less than 180 degrees. The diagonals of convex polygon lie within the polygon.
- A concave polygon has at least one of its interior angles to be more than 180 degrees. Also, not all the diagonals of the concave polygon lie within the shape.

### Types of Triangles

Triangles are also classified into six categories based on sides and angles. The names of different triangles are:

- Scalene triangle (All sides are unequal in length)
- Isosceles triangle (Any two sides are equal in length)
- Equilateral triangle (All the three sides are equal in length)
- Acute-angled triangle (All the three interior angles are less than 90 degrees)
- Obtuse-angled triangle (Any one of the three interior angles is more than 90 degrees)
- Right-angled triangle (Any one of the three interior angles is exactly equal to 90 degrees)

### Types of Quadrilaterals

A quadrilateral is a four sided, two dimensional, closed shape. It is also called a four sided polygon. It is categorized into different categories, such as:

- Square (All four sides are equal and all interior angles equal to 90 degrees)
- Rectangle (Opposite sides are equal and parallel to each other, interior angles are equal to 90 degrees)
- Parallelogram (Opposite sides are equal and parallel)
- Rhombus (All sides are equal and diagonals bisect at 90 degrees)
- Kite (Adjacent sides are equal and diagonals intersect at 90 degrees)
- Trapezium (Only one pair of opposite sides are parallel)

### Three – Dimensional Shapes

Above we have discussed all the two-dimensional shapes. Here we will see the 3d shapes mentioned in geometry.

Three dimensional shapes are determined by three major axes, i.e., x-axis, y-axis and z-axis. These are also called solids, since they appear as solid structures. The common solids, that are seen in everyday lives are:

- Sphere (A round shape)
- Cube (has 6 faces, 8 vertices, 12 edges and faces are in square shape)
- Cuboid (has 6 faces, 8 vertices, 12 edges and faces are in rectangular shape)
- Cone (1 circular base, 1 vertex and a curved surface)
- Cylinder (two parallel circular bases and a curved surface)

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## Shapes for Kids

In primary classes, kids are taught with basic shapes. Teachers can teach children different shapes, using examples of objects which we see in classrooms and homes. Some of the examples are given here:

- Square shaped tiles in the classroom
- Clock at house is circular or round in shape
- Rooftop of house is triangular
- Heart shaped biscuits
- Star shaped mirror

## Frequently Asked Questions on Shapes

### What are shapes?

In geometry, shapes are defined as the form or outline of an object that determines their properties.

### What are 2d shapes and 3d shapes?

Two dimensional shapes are flat shapes that are defined in the XY plane. Three dimensional shapes are solids that have thickness extended in z-axis.

### What are the different types of shapes?

The different types of shapes are 2d and 3d shapes, regular and irregular shapes, concave and convex shapes, closed and open shapes.

### What are the basic 16 types of shapes?

The basic shapes are: circle, square, rectangle, parallelogram, rhombus, kite, scalene triangle, isosceles triangle, equilateral triangle, acute triangle, obtuse triangle, right triangle, trapezoid, pentagon, hexagon.

### What are the basic 3d solids?

The basic 3d shapes are sphere, cube, cone, cuboid and cylinder.

### What are regular and irregular shapes?

A regular shape is uniform and has sides and angles equal. Irregular shape is non-uniform and has unequal sides and angles.