置換積分法②

問題次の不定積分を置換積分法で求めよ。$${\small (1)}~\int \sin^2{x}\cos{x} dx$$$${\small (2)}~\int \frac{\tan{x}}{\cos^2{x}} dx$$$${\small (3)}~\int xe^{x^2} dx$$$${\small (4)}~\int \frac{(\log x)^2}{x} dx$$