POINT OF SYMMETRY
Definition Of Point Of Symmetry
If a figure or graph is rotated about a point by 180° and yet looks identical to its original, that point is called the Point of Symmetry.
More About Point of Symmetry
If a figure has a point of symmetry, then its order of rotational symmetry will be 2.
Video Examples: Polar Axis Dialog
Example of Point of Symmetry
In the figure, a rectangle is rotated 1800 by a point.
The rectangle obtained after rotation matches with the original rectangle.
So, the point with which the rectangle is rotated is called the point of symmetry.
Solved Example on Point of Symmetry
Ques: Which of the figures has a point of symmetry?
Choices:
A. Graph 1
B. Graph 2
C. Graph 3
D. none of the above
Correct Answer: A
Solution:
Step 1: A figure or a graph when rotated by 180° looks similar to its original, it is said to have a point of symmetry.
Step 2: When Graph 1 is rotated through 180°, it matches the original figure.
Step 3: So, Graph 1 has point of symmetry.
Quick Summary
- Point of symmetry implies rotational symmetry of order 2.
- Rotating a figure with point symmetry by 180 degrees around that point results in the same figure.
🍎 Teacher Insights
Use physical manipulatives to demonstrate the 180-degree rotation. Emphasize the difference between point symmetry and other types of symmetry. Provide examples of real-world objects with point symmetry.🎓 Prerequisites
- Rotational Symmetry
- Angles
- Transformations
Check Your Knowledge
Q1: Which of the following shapes has a point of symmetry?
Q2: A figure is rotated 180 degrees about a point and looks identical to the original. What is this point called?
Frequently Asked Questions
Q: Does a square have a point of symmetry?
A: Yes, the center of the square is a point of symmetry.
Q: Does every figure have a point of symmetry?
A: No, only certain figures possess point symmetry. For example, a scalene triangle does not.