>>693

{log|tan(x/2)|}'={1/tan(x/2)}(1/2){1/(cos(x/2))^2}
=(1/2){cos(x/2)/sin(x/2)}{1/(cos(x/2))^2}
=1/{2sin(x/2)cos(x/2)}
=1/sinx

{log(x+√(x^2+1))}'={1/(x+√(x^2+1)}{1 +x/√(x^2+1)}=1/√(x^2+1)