Question 5
Given the line(s) of symmetry, find the other hole(s):
- A line of symmetry acts like a mirror line dividing a figure into two identical halves.
- If a figure is folded along its line of symmetry, the two halves coincide completely.
- The position of the second hole is found by reflecting the given hole across the line of symmetry at an equal perpendicular distance on the opposite side.
(a) Find the other hole for figure (a).
Step 1 · Reflect the Hole Across the Diagonal Line
Reflect the hole in the top-left section across the diagonal line of symmetry to obtain the corresponding hole in the bottom-right section.
(a) The other hole is in the bottom-right section.
(b) Find the other hole for figure (b).
Step 1 · Reflect the Hole Across the Horizontal Line
Reflect the hole in the bottom-right section across the horizontal line of symmetry to obtain the corresponding hole in the top-right section.
(b) The other hole is in the top-right section.
(c) Find the other hole for figure (c).
Step 1 · Reflect the Hole Across the Vertical Line
Reflect the hole on the left side across the vertical line of symmetry to obtain the corresponding hole on the right side.
(c) The other hole is on the right side.
(d) Find the other hole for figure (d).
Step 1 · Reflect the Hole Across the Diagonal Line
Reflect the hole in the top-right section across the diagonal line of symmetry to obtain the corresponding hole in the bottom-left section.
(d) The other hole is in the bottom-left section.
(e) Find the other hole for figure (e).
Step 1 · Reflect the Hole Across the Diagonal Line
Reflect the hole in the top-left section across the diagonal line of symmetry to obtain the corresponding hole in the bottom-right section.
(e) The other hole is in the bottom-right section.
- Unequal Distance: Placing the reflected hole at an unequal distance from the line of symmetry compared to the original hole.
- Non-Perpendicular Reflection: Shifting the hole parallel to the line of symmetry rather than reflecting it perpendicularly across the line.
More questions in FIO
Do you see any line of symmetry in the figures at the start of the chapter? What about in the picture of the cloud?
For each of the following figures, identify the line(s) of symmetry if it exists.
Punching Game
The fold is a line of symmetry. Punch holes at different locations of a folded square sheet of paper using a punching machine and create different symmetric patterns.
In each of the following figures, a hole was punched in a folded square sheet of paper and then the paper was unfolded. Identify the line along which the paper was folded. Figure (d) was created by punching a single hole. How was the paper folded?
Given the line(s) of symmetry, find the other hole(s):
Here are some questions on paper cutting. Consider a vertical fold. We represent it this way:
Vertical Fold
Similarly, a horizontal fold is represented as follows:
Horizontal Fold
After each of the following cuts, predict the shape of the hole when the paper is opened. After you have made your prediction, make the cutouts and verify your answer.
Trace each figure and draw the lines of symmetry, if any:
Copy the following on a dot grid. For each figure draw two more lines to make a shape that has a line of symmetry.
Find the angles of symmetry for the given figures about the point marked •.
(a) (b) (c)
Which of the following figures have more than one angle of symmetry?
Give the order of rotational symmetry for each figure:
Colour the sectors of the circle below so that the figure has:
(i) 3 angles of symmetry
(ii) 4 angles of symmetry
(iii) What are the possible numbers of angles of symmetry you can obtain by colouring the sectors in different ways?
Draw two figures other than a circle and a square that have both reflection symmetry and rotational symmetry.
Draw, wherever possible, a rough sketch of:
a. A triangle with at least two lines of symmetry and at least two angles of symmetry.
b. A triangle with only one line of symmetry but not having rotational symmetry.
c. A quadrilateral with rotational symmetry but no reflection symmetry.
d. A quadrilateral with reflection symmetry but not having rotational symmetry.
In a figure, is the smallest angle of symmetry. What are the other angles of symmetry of this figure?
In a figure, is an angle of symmetry. The figure has two angles of symmetry less than . What is its smallest angle of symmetry?
Can we have a figure with rotational symmetry whose smallest angle of symmetry is:
a. ?
b. ?