A Flat Circular Coil Having 16 Turns,each of Diameter 20 $\vec { B }$

A flat circular coil having 16 turns,each of diameter 20 cm,is in a uniform and steady 0.13-T $\vec { B }$ B field.
(a)Find the total magnetic flux through the coil when the field is perpendicular to the plane of the coil.
(b)If the coil is rotated in 10 ms so its plane is parallel to the $\vec { B }$ field vector,find the average induced emf in the coil.