In the given figure, $O$ is the centre of a circle. If ∠AOB=100∘ and ∠AOC=90∘ , then ∠BAC=?
In figure, ∠BOC, ∠BOA and ∠AOC formed the complete angle
In a circle, angle subtended by an arc at the centre is twice the angle subtended by the same arc at any point on the remaining arc of the circle.
i.e., in Figure,
Hence, Option A is correct.