Theorem 9.1 - Chapter 9 Class 9 Circles
Last updated at Feb. 13, 2025 by Teachoo
Last updated at Feb. 13, 2025 by Teachoo
Theorem 9.1 Equal chords of a circle subtend equal angles at the center. Given: A circle with center O. AB and CD are equal chords of circle i.e. AB = CD To Prove : ∠AOB = ∠DOC Proof : In ΔAOB & ΔDOC AO = OD AB = CD OB = OC ∴ ∆AOB ≅ ∆ DOC ∴ ∠ AOB = ∠ DOC Hence, Proved.
Theorems
Theorem 9.2 Important
Theorem 9.3 Important
Theorem 9.4
Theorem 9.5 Important
Theorem 9.6
Theorem 9.7 Important
Theorem 9.8
Theorem 9.9 Important
Theorem 9.10
Theorem 9.11 Important
Angle in a semicircle is a right angle Important
Only 1 circle passing through 3 non-collinear points
About the Author
Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 15 years. He provides courses for Maths, Science and Computer Science at Teachoo