4. Evaluate 1+12 dx with ordinary u-substitution technique. V1+22 5. We will evaluate dx in the following steps. (a) Using an appropriate trigonometric substitution, transform the above integral into csc 0 sec2 0 de. (b) Verify the following trigonometric identity: csc 0 sec' 0 = csc 0 + tan 0 sec 0. (c) Using the results in parts (a) and (b), plus the antidervative formlae, show that 1 + x2 V1+22 + 1 de = - In +V1+x2 + C