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Triangle Classification

Triangle Classification

Learn to classify triangles by their angles and sides. Master the six main triangle types and understand their unique properties and real-world applications.

Classification by Angles

Acute Triangle

All angles are less than 90°

Example:

60°, 70°, 50°

Properties:

  • All angles < 90°
  • Sharp-pointed appearance
  • Common in roof trusses

Right Triangle

One angle equals exactly 90°

Example:

90°, 60°, 30°

Properties:

  • One 90° angle
  • Has a hypotenuse
  • Foundation of trigonometry

Obtuse Triangle

One angle is greater than 90°

Example:

120°, 40°, 20°

Properties:

  • One angle > 90°
  • Wide appearance
  • Used in modern architecture

Classification by Sides

Scalene Triangle

All sides have different lengths

Example:

Sides: 3, 5, 7

Properties:

  • All sides different
  • All angles different
  • Most common type

Isosceles Triangle

Two sides have equal lengths

Example:

Sides: 5, 5, 8

Properties:

  • Two equal sides
  • Two equal base angles
  • Line of symmetry

Equilateral Triangle

All three sides are equal

Example:

Sides: 6, 6, 6

Properties:

  • All sides equal
  • All angles 60°
  • Three lines of symmetry

Practice Tools

Use our calculators to practice triangle classification and understand properties.

Continue Learning

Explore more triangle concepts and advanced properties.