Line of Symmetry and Reflection Symmetry

🌟 A line of symmetry is an imaginary line that divides a shape into two identical parts.

• If you fold the shape along this line, both halves will match perfectly.
• A shape can have one or more lines of symmetry, depending on its structure.
• This concept is often seen in geometry, design, and nature, where many shapes and patterns have symmetry.

🌟 A shape has reflection symmetry if it has at least one line of symmetry.

Examples of Line Symmetry:

• Rectangle: 2 lines of symmetry
  (One vertical and one horizontal)
• Square: 4 lines of symmetry
  (Vertical, horizontal, and two diagonals)
• Isosceles Triangle: 1 line of symmetry
  (A vertical line from the top to the base)
• Equilateral Triangle: 3 lines of symmetry
  (Each vertex to the midpoint of the opposite side)
• Circle: Infinite lines of symmetry
  (Any line that passes through the center splits the circle into two equal halves)

To check if a shape has line symmetry, imagine folding it along a line. If both sides match exactly, the shape has line symmetry.

Examples:

• ✅ Arrow Sign: Has a horizontal line of symmetry.
  The top and bottom halves are mirror images.
• ❌ Stop Sign with Hand: No reflection symmetry.
  The hand symbol does not divide evenly into two identical halves.

🌟 Exam Tip: Start by testing vertical, horizontal, or diagonal lines—these are the most common lines of symmetry. If none work, try other lines that pass through the center of the shape.

A line of symmetry splits a shape into two identical halves. There are key properties you must know:

• Mirror Points: Each point on one side of the line has a corresponding point on the opposite side.
• Equal Distance: Both points are the same distance from the line of symmetry.

This property is used in reflections, design, and geometry to create balanced shapes.

If you are given half of a shape and its line of symmetry, follow these steps to complete it:

1. Find a Key Point
   • Choose a key point (such as a vertex).
   • Draw a perpendicular line from the key point to the line of symmetry.
2. Find the Mirror Point
   • Measure the distance from the key point to the line of symmetry.
   • Double this distance and mark the mirror point on the opposite side of the line.
3. Connect the Points

• • Repeat for all key points.
  • Draw lines to connect the mirror points and complete the shape.