Answer:
Part a)

Part b)

Step-by-step explanation:
Part a)
As we know that car is moving with uniform speed
so here net tangential force must be zero while in radial direction the car is moving in circle so here we have

so we have

R = 285 m

now we have


Part b)
As we know that Police Man is experiencing the force only towards the center of the circle
So the net force is horizontal towards the center of the circle and hence it angle with vertical will be
