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Question 1 - Page 159 - Triangle Inequality & Construction of Circles - Chapter 7 Class 7 - A tale of three Intersecting Lines (Ganit Prakash)
Last updated at November 7, 2025 by Teachoo
Triangle Inequality & Construction of Circles
Class 7 (Ganita Prakash 1, 2 & old NCERT)
Chapter 7 Class 7 - A tale of three Intersecting Lines (Ganit Prakash)
- Definition
- Constructing Equilateral Triangle
- Constructing a Triangle when its Sides are given
- Figure it out - Page 150, 151
- Are Triangles Possible for any Lengths?
- Figure it out - Page 154
- Visualising the Construction of Circles
- Figure it out - Page 156
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Triangle Inequality & Construction of Circles
- Figure it out - Page 159
- Constructing Triangle when 2 Sides and the Included Angle are given
- Constructing Triangle when 2 Angles and the Included Side are given
- Do triangles always exist?
- Sum of angles of a triangle
- Angle Sum Property
- Exterior Angles
- Constructions Related to Altitudes of Triangles
- Figure it out - Page 170, 171
Transcript
Question 1 - Page 159 Can we use this analysis to tell if a triangle exists when the lengths satisfy the triangle inequality? If the given lengths satisfy the triangle inequality, then the sum of the two smaller lengths is greater than the longest length. This means that this will lead to Case 3 where the circles intersect internally, and so a triangle exists. Yes, absolutely. This analysis is the proof that the rule works. The "Triangle Inequality" is just another name for the condition in Case 3: sum of the two smaller lengths > longest length. Our analysis shows that when this condition is met, the circles will intersect (Case 3). Since the intersection point is what forms the triangle, this proves that if the lengths satisfy the Triangle Inequality, a triangle exists.
