Types of Triangles

In this lecture, we explored the four types of triangles: Equilateral, Isosceles, Right Angle, and Scalene. All triangles share the common feature of having three straight sides.

1. Equilateral Triangle

• Characteristics:
  • All three sides are the same length.
  • All three angles are 60 degrees.
• Identification:
  • Look for triangles with all sides marked with the same dashes.
  • Verify all angles are 60 degrees.
• Symmetry:
  • Three lines of symmetry.
  • Rotational symmetry of order 3 (triangle looks the same in three positions within a complete rotation).

2. Isosceles Triangle

• Characteristics:
  • Two sides are the same length.
  • Two angles are the same size.
• Identification:
  • Equal sides are often marked with dashes.
• Symmetry:
  • One line of symmetry.
  • No rotational symmetry.

3. Right Angle Triangle

• Characteristics:
  • Contains a right angle (90 degrees).
• Identification:
  • Right angle is usually indicated with a small square at the corner.
• Symmetry:
  • Typically no lines of symmetry or rotational symmetry.
  • If it is a right angled isosceles triangle, it will have one line of symmetry (two sides the same length).

4. Scalene Triangle

• Characteristics:
  • All three sides are of different lengths.
  • All three angles are of different sizes.
• Symmetry:
  • No lines of symmetry.
  • No rotational symmetry.

This summary captures the key points of the different types of triangles discussed in the lecture. Remember the unique features and symmetry properties for identifying each type.