In the given figure, O is the centre of the circle.
If the length of chord AB is equal to the radius of the circle; then ∠ACB is equal to :

1. 30°

2. 45°

3. 60°

4. 40°

The value of x in the following figure is :

1. 80°

2. 57°

3. 87°

4. 96°

In the given figure, O is centre of the circle.
If ∠AOC = 130°, then the value of x is :

1. 25°

2. 50°

3. 65°

4. 40°

In the given figure, O is the centre of the circle, ∠AOB = 40° and ∠BDC = 100°. The measure of ∠OBC is :

1. 40°

2. 80°

3. 60°

4. 20°