# Math՚s: Lines and Angles: Triangle: Meaning, Types and Properties (For CBSE, ICSE, IAS, NET, NRA 2022)

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## Triangle- Meaning

A triangle is a closed figure formed on a plane by joining three collinear points by three-line segments. It has six elements-

• Three angles formed on the three points. ∠ A, ∠ B and ∠ C in the given figure.
• Three sides that consist of the three-line segments. AB, BC and AC in the given figure.

## Types of Triangles

Triangles can be classified into different types on two bases-

### On the Basis of Sides

• Equilateral triangle: A triangle in which all the three sides are equal is called an equilateral triangle.
• Isosceles triangle: A triangle in which two sides are equal is called an isosceles triangle.
• Scalene triangle: A triangle in which all sides are of different lengths, is called a scalene triangle

### On the Basis of Angles

• Obtuse angled triangle: A triangle in which one of the angles is an obtuse angle is called an obtuse angled triangle or simply obtuse triangle.
• Right angled triangle: A triangle in which one of the angles is a right angle is called a right-angled triangle or right triangle.
• Acute angled triangle: A triangle in which all the three angles are acute is called an acute angled triangle or acute triangle.