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Angle Sum Property
Last updated at November 7, 2025 by Teachoo
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
- 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
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Angle Sum Property
- Exterior Angles
- Constructions Related to Altitudes of Triangles
- Figure it out - Page 170, 171
Transcript
Angle Sum PropertyWe looked at our triangle By Alternate interior angles ∠ XAY = ∠ B ∠ YAC = ∠ C Apply Since XY is a line Applying Linear Pair ∠ XAB + ∠ A + ∠ YAC = 180° ∠ B + ∠ A + ∠ C = 180° ∠ A + ∠ B + ∠ C = 180° Thus, we can say that Sum of all angles of a triangle is 180° We can use this property directly to find missing angles
