NCERT Solutions for Class 9 Maths Chapter 5 Introduction to Euclid's Geometry

The fifth chapter of NCERT Class 9 textbook gives a clear introduction to Geometry's also known as Euclid's Geometry along with its origin and the need for its application. The application of geometry to overcome issues that involved the overflowing of the river has been done. A brief description of the origin of geometry in India and other mathematicians who developed it has been mentioned. Euclid's geometrical theories have been detailed out, based on which the concepts exist. Basic principles relating to geometry have been laid out with examples supporting it. In the end, Euclid's geometrical postulates have been mentioned.

• Brief emphasis has been put at the beginning of the chapter to describe the origin and importance of geometry.
• Without geometry, the construction of dams, buildings, bridges would have been impossible.
• It is with the strong foundation laid by the eminent mathematicians that the theorems are developing.
• Thales, a Greek mathematician, proposed any angle formed on the diameter of a circle and touching the circumference of the circle will be a right angle.
• The elements of geometry have been segregated and mentioned in the book of Euclid.
• Euclid's geometry further explained the terminologies: Spheres, surfaces, curves, dimensions and points.
• The differentiation and relativity between Axioms and Postulates have been briefed.
• Common notions or Axioms are the assumptions of maths but not of geometry.
• On the other hand, the postulates are the assumptions specific to geometry.
• The chapter ends with highlighting the five main postulates of Euclid.