Line of Symmetry and Reflection Symmetry
Learn how to quickly spot and count lines of symmetry in any shape. Let's get started. 🚀
Video Lesson
Watch and learn the basics
Flashcards
Review key concepts visually
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🛎️ What is a Line of Symmetry?
- A line of symmetry divides a shape into two identical halves.
- If you fold the shape along the line, both sides match exactly.
🛎️ Lines of Symmetry in Common Shapes
- The number of lines depends on how many ways a shape can fold exactly in half.
- Squares have 4, rectangles have 2, and circles have infinite lines.
🛎️ How to Check for Reflection Symmetry?
- Try folding the shape along a line and see if both sides match exactly.
- If you can find at least one line of symmetry, the shape has reflection symmetry.
🛎️ Key Features of a Line of Symmetry
- Every point on one side has a mirror point on the other side.
- Mirror points are the same distance from the line of symmetry.
🛎️ Completing a Shape Given Line of Symmetry
- Measure the distance from a point to the line of symmetry.
- Plot the mirror point the same distance on the other side.
- Connect the points to complete the shape.
Practice Questions
Test your understanding
How many lines of symmetry does a square have?
Correct! 🎉 +10 pointsNot quite right
A square has 4 lines of symmetry—two along its diagonals and two through the midpoints of opposite sides.
Which shape has an infinite number of lines of symmetry?
Correct! 🎉 +10 pointsNot quite right
A circle has an infinite number of lines of symmetry because it can be divided into two identical halves through any diameter.
True or False: An isosceles triangle has three lines of symmetry.
Correct! 🎉 +20 pointsNot quite right
The statement is false because an isosceles triangle has only one line of symmetry, which divides it into two identical halves.
If point P is 3 cm away from the line of symmetry, where will its mirror point P' be?
Correct! 🎉 +20 pointsNot quite right
The mirror point P' will be 3 cm away on the opposite side of the line of symmetry, maintaining the same distance as point P.
Does this shape have reflection symmetry?
Correct! 🎉 +20 pointsNot quite right
The shape has reflection symmetry, meaning it can be divided into two identical halves by a line of symmetry.
How many lines of symmetry does a regular pentagon have?
Correct! 🎉 +30 pointsNot quite right
A regular pentagon has five lines of symmetry, each passing through a vertex and the opposite side’s midpoint.
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Interactive Activity
Fold shapes to test for symmetry
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