Интеграл cos^2x*dx/sin^4x интеграл dx/cos^4x*sin^2x

[latex]\int \frac{cos^2xdx}{sin^4x}=\int \frac{cos^2x}{sin^2x}\cdot \frac{dx}{sin^2x}=\int ctg^2x\cdot \frac{dx}{sin^2x}=[t=ctgx,\; dt=-\frac{dx}{sin^2x}]=\\\\=-\int t^2\cdot dt=-\frac{t^3}{3}+C=-\frac{ctg^3x}{3}+C\\\\\\\int \frac{dx}{cos^4x\cdot sin^2x}=\int \frac{\frac{dx}{cos^6x}}{\frac{cos^4xsin^2x}{cos^6x}}=\int \frac{(\frac{1}{cos^2x})^2\cdot \frac{dx}{cos^2x}}{tg^2x}=\\\\=[t=tgx,dt=\frac{dx}{cos^2x},1+tg^2x=\frac{1}{cos^2x}]=\int \frac{(1+t^2)^2dt}{t^2}=\int \frac{1+2t^2+t^4}{t^2}dt=[/latex] [latex]=\int (t^{-2}+2+t^2)dt=\frac{t^{-1}}{-1}+2t+\frac{t^3}{3}+C=-\frac{1}{tgx}=2tgx+\frac{1}{3}\cdot tg^3x+C[/latex]