(i) In Figure (1), O is the centre of the circle. If ∠OAB=40∘ and

1.	(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.
Answer» (i) In Figure (1), O is the centre of the circle. If $∠ OAB = 40^{\circ}$ and $∠ OCB = 30^{\circ}$ , find $∠ AOC$ . (ii) In Figure (2), A, B and C are three points on the circle with centre O such that $∠ AOB = 90^{\circ}$ and $∠ AOC = 110^{\circ}$ . Find $∠ BAC$ .

(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.

Answer»

(i) In Figure (1), O is the centre of the circle. If $∠ OAB = 40^{\circ}$ and $∠ OCB = 30^{\circ}$ , find $∠ AOC$ .

(ii) In Figure (2), A, B and C are three points on the circle with centre O such that $∠ AOB = 90^{\circ}$ and $∠ AOC = 110^{\circ}$ . Find $∠ BAC$ .