grade V

In this section we all are going to discuss about geometry help and lines of symmetry which are usually studied in grade V. Here I am going to tell you the best way of understanding these topics.Now let us start with basics about geometry:
Geometry is on the whole about the points, lines, angles, areas, volumes etc. And to learn it we should keep some points in our mind. A point is represented as a dot in a plane, a line is described as the collection of points, a line does not have any end point, a line segment is a part of line that has two end points, a ray is defined as a line which starts from a point and extends in a direction forever, when two rays start from same point then they form an angle between them, plane can be defined as a flat surface that extends forever. Triangle, circle, quadrilateral, polygons etc. are the examples of geometrical shapes.
Now let us talk in detail about Lines of symmetry. When an image or a figure is folded from the middle and if the half part is completely symmetric to the other half part or in other words one half part is mirror image of the other part then that figure or image is said to be symmetric. And when you unfold that figure or image you will see a line of crease, that line is known as line of symmetry. Let’s see lines of symmetry of some shapes.
Lines of symmetry of triangles:
In a triangle we can have 3, 1 or 0 number of lines of symmetry.
                          
Equilateral triangle ( having all sides and angles equal )
It has 3 lines of symmetry.
                     
Isosceles triangle ( having two sides and angles equal )
It has 1 line of symmetry
                
Scalene triangle ( having no sides and angles equal )
It has no lines of symmetry

Lines of symmetry of quadrilaterals:
There are many types of quadrilaterals

                 
Square ( having all sides and angles equal and also all angles are 90 degrees )
It has 4 lines of symmetry.
         
             
Rectangle ( having opposite sides equal and all angles are 90 degrees )
It has 2 lines of symmetry.

            
Irregular Quadrilateral
It has no lines of symmetry

                  
Kite
It has 1 line of symmetry.

                     
Rhombus ( having all sides equal in length )
It has 2 lines of symmetry.

Lines of symmetry of regular polygons:
In a regular polygon we have all sides and angles equal to each other.

                                       
Regular Pentagon ( having 5 sides )
It has 5 lines of symmetry

                 
Regular Hexagon ( having 6 sides )
It has 6 lines of symmetry

               
Regular Heptagon ( having 7 sides )
It has 7 lines of symmetry

                  
Regular Octagon ( having 8 sides )
It has 8 lines of symmetry

Lines of symmetry of circles:
A circle has infinite number of lines of symmetry and the lines of symmetry must be go through the radius of circle.

              

In upcoming posts we will discuss about Probability and Statistics. Visit our website for information on syllabus of economics for ICSE class 12