NCERT Solutions
Class 9 - Mathematics - Chapter 9: CIRCLES
EXERCISE 9.1

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Question. 1

Recall that two circles are congruent if they have the same radii. Prove that equal chords of congruent circles subtend equal angles at their centres.

Answer:

Prove exactly as Theorem 9.1 by considering chords of congruent circles.

Question. 2

Prove that if chords of congruent circles subtend equal angles at their centres, then the chords are equal.

Answer:

Use SAS axiom of congruence to show the congruence of the two triangles.