Đáp án:

• \( \int \frac{\sin^3 x}{\cos^2 x} \, dx = \int \sin x \frac{ (1 - \cos^2 x)}{\cos^2 x} \, dx \)

• Đặt \( t = \cos x \Rightarrow dt = -\sin x \, dx \)

• \( I = \int \frac{t^2 - 1}{t^2} \, dt =  t + \frac{1}{t} + C = \cos x + \frac{1}{\cos x} + C \)