∫ sin^3x*cosx dx от 0 до Pi/4
[m]\int_{0}^{\pi/4} \sin^3\ x \cdot \cos\ x\ dx[/m] Замена sin x = y; dy = (sin x)' = cos x dx Пределы интегрирования: y(0) = 0; y(π/4) = sqrt(2)/2 [m]\int_{0}^{\sqrt{2}/2} y^3\ dy = \frac{y^4}{4}|_{0}^{\sqrt{2}/2} = \frac{2^2}{2^4 \cdot 4} - 0 = \frac{4}{64} = \frac{1}{16}[/m]