سیگما

`Q=int (sin(x+pi/4))/(sinx cosx) dx`
`Q=int ((sinx+cosx)/sqrt(2))/(sinx cosx) dx`
`t=tan(x/2)`
`sinx=(2t)/(1+t^2)`
`cosx=(1-t^2)/(1+t^2)`
`dx=(2dt)/(1+t^)`
`Q=sqrt(2)/2 int ((2t+1-t^2)/(t^2+1))/((2t(1-t^2))/(1+t^2)^2) (2)/(1+t^2) dt`
`Q=sqrt(2) int (2t+1-t^2)/(2t-2t^3) dt`
`Q=int 1/(sqrt(2)t)-sqrt(2)/(t^2-1) dt`
`Q=sqrt(2)/2lnt-sqrt(2)arctanh(t)`