A line segment is commonly defined as a line having two endpoints with a definite length. Chapter 12 Triangles focuses on one shape formed by three non-parallel line segments consisting of a particular angle between them. Various types of triangles depend on the size of the segments. It is a two-dimensional shape and also known as a polygon with the least number of sides. A triangle can always be divided into two right-angled triangles, irrespective of its orientation. It consists of three angles which vary in measurement, but the sum of all the three interior angles is always 180°.
Chapter 12-Triangles talks about the Classification of triangles into 6 types based on both sides and angles. Depending on the size measurement, it is classified into three types: scalene, equilateral, and isosceles triangles. The triangle, which has all the sides of a different size, is termed a scalene triangle. The triangles with all sides are equal, and two equal sides are equilateral and isosceles triangles, respectively.
This chapter further consists of the Classifications based on the angles of the triangles. A triangle is classified based on angles. Acute, right and obtuse triangles are the three types of triangles. When all the constituting three angles of a triangle are acute, it is known as an acute-angled triangle, whereas in the case of right and obtuse, if any one of the angles in right and obtuse angle, it is known as a right-angled and an obtuse-angled triangle respectively.