6. (**) (a) (5 marks) Express f'(x) in terms of g(x) and its derivatives, where f(x) = Ing(x). (b) Hence, find i. (3 marks) dx, T /4 2 +1 ii. (5 marks) cot(x) + tan(x) dx TT / 4 (c) (7 marks) Find the function y(t) which satisfies dy t dt t2 + 1 - cot(t) - tan(t), for 0