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A 2D shape or a two-dimensional shape is a shape with length and width that can be drawn on a flat surface or a piece of paper. The determination of every point of an object with the help of minimum coordination is known as dimension.
- 2D shapes consist of curved shapes and polygons.
- 2D shapes don't have any thickness.
- They have only sides, corners, and curved boundaries.
- Examples of 2D shapes are windows, sheets, clocks, etc.
Read More: Edges, Faces, and Vertices
| Table of Content |
Key terms: 2D, Shapes, Sides, Height, Length, Breadth.
Definition of 2D shapes
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A two dimensional shape is the one that has vertical and horizontal axes (y axis and x axis). They have width and length without height or thickness.
- They are explained through horizontal and vertical axes.
- They are on planar surfaces so cannot be held.
- A triangle, a square and a circle are examples of 2D shapes.
Read More: Circles
Difference between 2D and 3D shapes
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| 2D shapes | 3D shapes |
|---|---|
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Read More: Similarities of Triangle
Types and properties of 2D shapes
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2D shapes consisting of various types and properties have been mentioned in detail as follows–
- Circle: Closed 2D shape consists of no corners or edges, only curved lines. The area of a circle is measured as 2πr2. It has a fixed radius and diameter.
Circle
Properties:
- Circles consist of circumference, radius, diameter.
- They have completed round with a single curved line.
- The total angle of a circle is equal to 360 degrees.
- Almost infinite axes of the symmetry going through the center in a circle.
- The circle has constant radius.
- Triangle: It is the simplest polygon with a flat surface and three sides, vertices, and angles. The area of a triangle is measured as ½ (base x height).
Triangle
Properties:
- The interior of the polygon is equal to 180 degrees.
- It can have no, 2 or 3 equal sides.
- It can have up to 2 axes of symmetry.
- Square: It is a four-sided polygon with four equal angles and sides. The bisecting angle of the diagonals of a square is 90 degrees.
Square
Properties:
- Equal four sides.
- The sum total of the four angles is 90 degrees.
- Four axes of symmetry.
- Opposite sides are parallel to each other.
- Rectangle: It is a four-sided polygon with only the opposite sides being equal and parallel. The angles of the rectangle are equivalent to 90 degrees.
Rectangle
Properties:
- The sum total of the four angles is equal to 90 degrees.
- Four axes of symmetry.
- 2 sets of 2 equal sides.
- The diagonal bisects each other and are of equal length.
- Diagonals bisect each other at an obtuse angle and an acute angle.
Read More: Pythagoras Theorem
Perimeter of 2D shapes
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In the following table the perimeters of few 2D shapes have been mentioned for better understanding–
| Shapes | Perimeter |
|---|---|
| Circle | 2πr |
| Triangle | Sum of three sides |
| Square | 4 (side) |
| Rectangle | 2 (length + breadth) |
| Rhombus | 4 (side) |
| Parallelogram | 2 (base + side) |
Read More:
| Related Articles | ||
|---|---|---|
| Areas Related to Circles | Perimeter of a Circle | Circumference of a Circle |
Solved Examples
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Example 1: Find the area and perimeter of a rectangle whose length is 10 cm and breadth is 5 cm. (2 Marks)
Solution: length of the rectangle = 10 cm
The breadth of the rectangle = 5 cm
Area of the rectangle = length x breadth = 10 x 5 = 50 cm2
Perimeter of the rectangle = 2 x ( length + breadth )
= 2 x (10 + 5) = 2 x 15
= 30 cm
Example 2: Find the area of a square whose length of the sides are 4 inches. (2 Marks)
Solution: length of the sides = 4 inches
Area of square = (side)2
= (4)2 = 16 in 2
Things to Remember
- 2D shapes don't have any thickness, they are totally flat.
- 2D shapes can be calculated by their length and width.
- A polygon with four edges and vertices is known as quadrilateral.
- A polygon with five straight lines and interior angles equal to 540 degrees is known as a pentagon.
- An example of a one dimensional shape is a straight line.
- A square is also known as a 2D regular quadrilateral.
- Pentagon can be regular and irregular in types.
Sample Questions
Ques: If the radius of a circle is 7 cm. calculate the area. (2 Marks)
Ans: radius of a circle = 7cm
Area of a circle =πr2
(22/7) x 72
22 x 7 = 154cm2
Ques: Find the perimeter, area, and length of the diagonal of a square whose side measures 6cm. (2 Marks)
Ans: length of each side of the square (a) = 6cm
Area = a2
62 = 36
Perimeter = 4a
4 x 6 = 24cm
Diagonal = a√2
√2 x 6 = 8.485cm
Ques: What are the different types of a triangle? (2 Marks)
Ans: triangles can be classified into three types based on the length of the sides, namely, scalene, isosceles and equilateral. Triangles can also be classified based on the measurement of the angles, namely, acute, right, and obtuse triangles.
Ques: What are the properties of the hexagon? (2 Marks)
Ans: hexagon comes under the category of polygon with six sides, angles, and vertices. The properties of the hexagon are:
- It has six sides and angles which can be equal or unequal
- It has up to six axes of symmetry
Ques: Is the circle a polygon? Give a reason for your answer (2 Marks)
Ans: polygon is a closed figure having more than two sides. Polygon consists of a finite number of line segments connected to each other. Circle is a closed curved shape that consists of a radius and diameter and is not made up of straight lines. Thus circle is not a polygon. Example of the polygon is a triangle, square, rectangle, hexagon, etc.
Ques: Why does a polygon have more than two sides? (2 Marks)
Ans: polygons are closed 2D shapes formed by straight lines which result in creating angles between them. Closed figures require more than two straight lines to be drawn. If both the straight lines are connected together, the angle that will be created between the lines will be zero and thus the resulting figure will be a straight line.
Ques: What is a quadrilateral? (2 Marks)
Ans: quadrilateral is a polygon that can be drawn by connecting four straight lines. It has four sides, vertices, and angles. The sum total of the interior angles of quadrilaterals is equal to 360 degrees. As the length of the sides may not be equal, there can be different types of quadrilaterals based on angles and sides.
Ques: What are the two types of 2D shapes? (2 Marks)
Ans: 2D shapes can be divided into regular and irregular 2D shapes based on the interior angles and the length. Regular 2d shapes are those whose interior angles are the same and the length of all their sides is equal. Irregular 2D shapes are those where the length of all the sides and the measurement of the interior angles are all unequal.
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