81 - 72 Evaluate the integral: da 622 (A) Which trig substitution is correct for this integral? Ox = 81 tan(0) Ox = 9 tan(0) Ox = 81 sin(0) Ox = 9 sin(0) Ox = 9 sec(0) Ox = 81 sec(0) (B) Which integral do you obtain after substituting for a and simplifying? Note: to enter 0, type the word theta. (C) What is the value of the above integral in terms of 0? + C (D) What is the value of the original integral in terms of a? C