2.a. ii) remember taylor's formula: use taylor's formula to calculate the exact values of higher derivatives {f'[0], f''[0], f'''[0], …, f[0], f[0]} of the function f[x] defined by the power series x/2 + x^2/12 + x^3/240 + x^4/10080 + … + (k x^k)/(2 k)! + … .