Theorem 9.1 - Chapter 9 Class 9 Circles

Last updated at August 5, 2026 by

Theorem 9.1 - Class 9 - Equal chords subtend equal angles at center - Theorems

 

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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.

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