Sir please help me to solve the ncert class 9th solution of chapter Introduction To Euclid’s Geometry .How I solve this question of exercise 5.1 question number 2. Find the simplest and easiest solution of this question. also find the best and easiest solution of this question. Give a definition for each of the following terms. Are there other terms that need to be defined first? What are they, and how might you define them? (i) parallel lines (ii) perpendicular lines (iii) line segment (iv) radius of a circle (v) square.