Learn in your speed, with individual attention - Teachoo Maths 1-on-1 Class

Theorems

Theorem 6.1

Theorem 6.6

Theorem 6.2 Important Deleted for CBSE Board 2024 Exams

Theorem 6.3 Deleted for CBSE Board 2024 Exams

Theorem 6.4 Deleted for CBSE Board 2024 Exams

Theorem 6.5 Important Deleted for CBSE Board 2024 Exams

Theorem 6.7 Important Deleted for CBSE Board 2024 Exams You are here

Theorem 6.8 Deleted for CBSE Board 2024 Exams

Chapter 6 Class 9 Lines and Angles

Serial order wise

Last updated at May 29, 2023 by Teachoo

Theorem 6.7 :- The sum of all angles are triangle is 180°. Given :- Δ PQR with angles ∠1, ∠2 and ∠3 Prove :- ∠1 + ∠2 + ∠3 = 180° Construction:- Draw a line XY passing through P parallel to QR Proof: Also, for line XY ∠1 + ∠4 + ∠5 = 180° ∠1 + ∠2 + ∠3 = 180° Hence, sum of all angle of a triangles are equal. Hence proved