Evaluate the following integral using trigonometric substitution. 21 1441 - x2 dx 21 What substitution will be the most helpful for evaluating this integral? O A. x =21 sec 0 O B. x = 21 tan 0 O C. x = 21 sin 0 Rewrite the given integral using this substitution. 21 1441 - x dx = () de 21 2 (Simplify your answers. Type exact answers.) Evaluate the integral. 21 441 - x dx = (Type an exact answer.) 21 2