A triangle is a polygon. It is a closed 3-sided shape made up of straight lines. The ‘tri-’ part of the word triangle means three. A triangle has 3 sides and 3 angles. Interior angles are the angles ...

Discusses the properties and types of triangles, explaining that a triangle is a closed figure with three sides and angles. It categorizes triangles into equilateral, isosceles, scalene, obtuse, right ...

Class 9 Maths Chapter 6 Lines and Angles is available here for download in PDF format. We have provided here the latest edition of the chapter which is published by the NCERT on its official website.

Ivo G. Rosenberg, Frank Stenger, A Lower Bound on the Angles of Triangles Constructed by Bisecting the Longest Side, Mathematics of Computation, Vol. 29, No. 130 (Apr., 1975), pp. 390-395 ...