minh lam cho
day la tp lien ket no ko ra dai hoc dau
ma pai de bai la zi ko nua
[TEX]I=\int\limits_{0}^{pi/4}\frac{cosx}{sinx+cosx}dx[/TEX]
nhu vay thi giai zi nek
[TEX]ta co J=\int\limits_{0}^{pi/4}\frac{sinx}{cosx+sinx}dx[/TEX]
ta lay [TEX]I+J=\int\limits_{0}^{pi/4}\frac{cosx+sinx}{cosx+sinx}dx=\int\limits_{0}^{pi/4}dx=\frac{pi}{4}[/TEX]
va ta lay [TEX]I-J=\int\limits_{0}^{pi/4}\frac{cosx-sinx}{cosx+sinx}dx[/TEX](cai nay ban biet tinh no chu tu tinh nhe)
xong ban dua len he cai ban casio ra I va J la xong ak