Circle and a Tangent

Q. $\text{From the given figure, find}\angle AOB\text{(in degrees )}.$

1. 140

Q. A tangent to a circle is a line that intersects the circle in only one point.

1. True
2. False
3. Either
4. Neither

Q. P is a point on a circle whose longest chord is AB. If P doesn't coincide with A or B, then $\angle APB=$ .

1. 90${}^{\circ }$
2. 100${}^{\circ }$
3. 80${}^{\circ }$
4. 75${}^{\circ }$