Question

Theorem I: Equal chords
angles at the centre.
circle subtend equal angles at the centre​

Answer 1

$\huge\red{here\;is\;your\;answer}$

In ΔAOB and ΔCOD,

AB=CD............... (Given)

AO=CO.............. (radius)

OB=OD.............. (radius)

By S.S.S congruency, ΔAOB≅ΔCOD

⇒∠AOB=∠COD.

$\huge{hope\;it\;helps}$