About Lesson

Exterior angle property of a triangle:

   If any side of a triangle is produced then the exterior angle so formed is equal to the sum of the interior opposite angles.

  • A triangle in which all three sides are equal length is called an equilateral triangle and its each angle is of measure 60°.

  • A triangle in which two sides are of equal length is called an isosceles triangle and its angles opposite equal sides are equal.