Revision Notes For CBSE Class 9 Math Chapter -7 Triangles

A triangle is a plane figure with three straight sides and three angles. The sum of angles of a triangle is equal to 180 degrees and the exterior angles of a triangle are always equal to 360 degrees. In a triangle, the sum of the angles is always greater than the length of the third angle. The area of a triangle is given by the formulae:

½ * base * height.

A triangle is classified into different types based on their sides and angles.

  • Equilateral Triangle
  • Isosceles triangle
  • Scalene Triangle
  • Acute angled Triangle
  • Right angle Triangle
  • Obtuse-angled Triangle

Check here for the free CBSE Class 9 Math revision notes for Chapter 7- Triangles

Class 9 Math Chapter 7- Triangles
Class 9 Math Chapter 7- Triangles

For more information about the Triangles, click on the below-mentioned links.


Practise This Question

The probabilities of different faces of a biased dice to appear are as follows
Face number123456Probability0.10.320.210.150.050.17
The dice is thrown and it is known that either the face number 1 or 2 will appear.  Then, the probability of the face number 1 to appear is