Đặt \(M=\int_{0}^{\frac{\pi}{2}}xcosxdx; N=\int_{0}^{\frac{\pi}{2}}sin^2xcosxdx\) Tính M Đặt \(\left\{\begin{matrix} u=x\\ dv=cosxdx \end{matrix}\right.\Rightarrow \left\{\begin{matrix} du=dx\\ v=sinx \end{matrix}\right.\) \(M=xsinx\bigg |^{\frac{\pi}{2}}_0-\int_{0}^{\frac{\pi}{2}}sinxdx=\frac{\pi}{2}+cosx\bigg |^{\frac{\pi}{2}}_0=\frac{\pi}{2}-1\) Tính N Đặt \(t=sinx\Rightarrow dt=cosxdx\) Đổi cận \(\left\{\begin{matrix} x=\frac{\pi}{2}\Rightarrow t=1\\ x=0\Rightarrow t=0 \end{matrix}\right.\) \(N=\int_{0}^{1}t^2dt=\frac{t^3}{3}\bigg |^1_0=\frac{1}{3}\) Vậy \(I=M+N=\frac{\pi}{2}-\frac{2}{3}\)