(17) (a): If f is continuous and f f(x)dr = 4, compute forf(x] )dr. (b): If a and b are positive numbers, show that [5 marks] DUE DATE: 30TH, DECEMBER, 2021 (18) Use the substitution u = # -r to show that If (sin x)de = 7 f (sin z)da. Then compute r sinc 1 + cos- I -de. 5 marks]