In Figure, AO=OB (Radii)
Therefore, ∠OAB = ∠OBA
In ∆ AOC,
OA = OC
x + z + y + z + x + y = 1800
2x + 2y + 2z = 1800
x + y + z = 900 Therefore, ∠OAC + ∠ABC = 900
If A, B, C are three points on a circle with centre O such that ∠AOB=90o and ∠BOC=120o, then ∠ABC=
(i) In figure (1), O is the centre of the circle. If ∠OAB=40∘ and ∠OCB=30∘. Find ∠AOC.
(ii) In figure (2), A,B and C are three points on the circle with centre O such that ∠AOB=90∘ and ∠AOC=110∘. Find ∠BAC.
In the picture O is the centre of the circle and A, B, C are points on it. Then ∠OAC+∠ABC equals ___