Question

In the given figure, the line of symmetry is given as a dotted line. Complete the figure and name the final figure you get after the completion of the figure.

Answer 1

Hint: Think of the basic definition of the line of symmetry and the property that line of symmetry acts as a plane mirror such that one side of the body is that object and the other side is the image of the object. If needed, a diagram could also be used for better visualisation.

Complete step-by-step answer:
Before starting with the solution, let us discuss the elements of symmetry and when a body is said to be symmetric or asymmetric. First, we will discuss the two major elements of symmetry, which are the line of symmetry and axis of symmetry.
The "Line of Symmetry" is the imaginary line through the body, which divides the body into two equal halves such that the parts on each side of the body are the mirror images of each other. While the axis of symmetry is an axis passing through the body about which the rotation of the body gives the exact identical figure as the initial one, provided the angle of rotation is less than , and the number of times the figure is repeated while rotating it by is the order of the rotational symmetry.
If a body consists of at least one of the elements of symmetry mentioned above is said to be symmetric. We can represent this diagrammatically as:

Now let us start the solution to the above question by drawing the diagram of the complete figure using the property that the line of symmetry divides the body into two parts, which are mirror images of each other.

Now from the above figure, it is clear that the above image of an 8 sided polygon, and we know that the name of the eight-sided polygon is the octagon.

Note: Remember that it is possible that a figure can have multiple elements of symmetry. For example a circle has an infinite number of lines of symmetry and one axis of rotational symmetry with infinite order of rotational symmetry.