問題：次の式を計算せよ
- (1) \( \displaystyle \int \dfrac{1}{1 + \cos x} dx \)
- (2) \( \displaystyle \int \dfrac{1}{\sin x} dx \)
- (3) \( \displaystyle \int \dfrac{1}{\sin x + \cos x + 1} dx \)
- (4) \( \displaystyle \int \dfrac{1}{\cos x} dx \)
- (5) \( \displaystyle \int \dfrac{1 - \sin x}{\sin x\cos x} dx \)