] 8. Evaluate ) [ 22 (x +4)3 dr in the following steps. (a) Set up a Trigonometric Substitution with an appropriate right triangle and relation between x and the reference angle 0. Transform the above integral into si sin tan do. (b) Using cos + sin 0 = 1, verify the following trigonometric identity: sin tan = sec 0 + cos 0 5] (c) Using the results in parts (a) and (b), plus the given formula sheet, evaluate x2 dx. (x+4)3