Consider: Implementing a u-substitution SELECT ALL AP technique to integrate inevitably involves at A) If we set u = tan a then B) If we set u = cos a then least two important questions: has the u- substitution been done correctly, and is the u- du = sec (x)dx ptan(I) substitution helpful/or successful in cos2 x dx = e" du completing the integration. C) If we set u = tana then D) none of these tan(I) cos' x etan(I) de = / e"du cosa In the following choices, we limit the analysis to just wether or not the u-substitution is done