Замена 1 + 4sin x = t; dt = 4cos x dx
[m]\int \sqrt{1+4 \sin x} \cdot \cos x\ dx = \frac{1}{4} \int \sqrt{t}\ dt = \frac{1}{4} \int t^{1/2}\ dt = [/m]
[m]= \frac{1}{4} \cdot \frac{t^{3/2}}{3/2} + C = \frac{1}{4} \cdot \frac{2}{3} \cdot t^{3/2} + C = \frac{1}{6} \cdot (1 + 4 \sin x)^{3/2} + C[/m]