関連ワード:  class 9 maths example 2 chapter 1    class 9 maths chapter 2 example 10    class 9 maths chapter 2 example 14    class 9 maths chapter 2 example 11    class 9 maths chapter 2 example 13    class 9 maths chapter 2 example 15    class 9 maths chapter 2 example 18    class 9 maths chapter 2 example 17    class 9 maths chapter 10 example 2 heron's formula    class 9 maths chapter 12 example 2