About Lesson

Properties of triangle

  • A closed figure formed by joining three non- collinear points is called a triangle.

  • A triangle with three unequal sides is called a scalene triangle.

  • A triangle with two equal sides is called an isosceles triangle.

  • A triangle with all its three sides equal is called an equilateral traingle. 

  • A triangle with all the three sides acute angles is an acute angled triangle.qAA triangle with one obtuse angle and two acute angles is called an obtuse angled triangle.

  • A triangle with one right angle and two acute angles is called a right angle. 

  • A median of a triangle is a line segment joining a vertex to the mid- point of the side opposite to that vertex.

  • An altitude of a triangle is the perpendicular drawn from a vertex to the opposite side( produced if necessary)

  • Angle sum property of a triangle : The sum of the angles of a triangle is 180°