If the two chords in a circle are equal, then the angle it subtends at the centre is same.
Equal chords subtend equal angles at the centre of the circle.
Let us consider two chords AB and PQ which are of equal length.
Now, Join the ends of the chords to the centre of the circle.
In ΔAOB and ΔPOQ,
OA = OP = r (radius of the circle)
Similarly,
OB = OQ = r (radius of the circle)
and, AB = PQ (Given in the statement)
∴ΔAOB ≅ ΔPOQ
∴By C.P.C.T., ∠AOB = ∠POQ.
∴We can say that the angle subtended by equal chords at the centre is equal.