RS Aggarwal Solutions for Class 9 Chapter 8 “Triangles”, a triangle is a polygon with three edges and three vertices. It is one of the basic shapes in geometry. A triangle with vertices A, B, and C is denoted. In Euclidean geometry, any three points, when non-collinear, determine a unique triangle and simultaneously, a unique plane. A triangle is a shape having three angles and three sides. It is mainly divided based on the number of sides and angles it possesses. Different types of triangles based on the number of sides are scalene triangles, Isosceles triangles, Equilateral triangles, and the triangles based on the angles are obtuse-angled triangle, acute-angled triangle and Right-angled triangle. Some of the applications of Triangles are architecture, design of buildings, the height of bridges and finding the area of geometric structures.