A sector of a circle with radius 21 cm has an area of 280\(cm^{2}\). (a) Calculate, correct to 1 decimal place, the perimeter of the sector. (b) If the sect...

A sector of a circle with radius 21 cm has an area of 280\(cm^{2}\).

(a) Calculate, correct to 1 decimal place, the perimeter of the sector.

(b) If the sector is bent such that its straight edges coincide to form a cone, calculate, correct to the nearest degree, the vertical angle of the cone. [Take \(\pi = \frac{22}{7}\)].