Triangle
A figure or region enclosed by three line segments is called a triangle.
The point where any two sides of a triangle meet is called a vertex. The line segment joining two vertices is called a side of the triangle.
Triangle
△ABC
A triangle has three sides and three vertices.
🔹 Types of Triangles Based on Sides
According to sides, triangles are of three types:
Scalene Triangle
Isosceles Triangle
Equilateral Triangle
Scalene Triangle
AB ≠ BC ≠ CA
∠A ≠ ∠B ≠ ∠C
In this triangle, all sides and all angles are unequal.
Isosceles Triangle
AB = AC ≠ BC
∠B = ∠C ≠ ∠A
In this triangle, any two sides and the angles opposite to them are equal.
Equilateral Triangle
AB = BC = CA
∠A = ∠B = ∠C = 60°
In this triangle, all sides and all angles are equal.
🔹 Types of Triangles Based on Angles
According to angles, triangles are of three types:
Acute-angled Triangle
Right-angled Triangle
Obtuse-angled Triangle
Acute-angled Triangle
∠A < 90°, ∠B < 90°, ∠C < 90°
In this triangle, all the angles are less than 90°.
Right-angled Triangle
∠A = 90°
In this triangle, one angle is exactly 90°.
Obtuse-angled Triangle
∠A > 90°
In this triangle, one angle is greater than 90°.