I need help with these two, I don't get it.

1. Use Newton's method to find a zero of the function, f(x)=x^3-3 x+6, using x[0]=-1. Explain why the method fails. Fix it so that it does find a zero.

2. In the figure, the length of the chord AB is 4 cm and the length of the arc AB is 5 cm. Find the central angle \[Theta], in radians, correct to 6 decimal places.

Thanks