If an arc of a circle subtends a right angle at any point on the remaining part of the circle, then the arc is a :

1. minor arc

2. major arc

3. semi-circle

4. none of these

ABCD is a cyclic quadrilateral such that AB is a diameter of the circle circumscribing it and ∠ADC = 125°, then ∠BAC is equal to :

1. 35°

2. 40°

3. 45°

4. 55°

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°