word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word word
コメント
24、分母分子をcosxで割って、tanx=t置換でかなり楽に解けました
12について
与式=I、与式の分子を(cosx)^4に変えたもの=Jとして、I+JとI-Jを求めることで楽に解けました
面白い積分を沢山載せていただいてありがとうございます!