I need help in the following problems:

1. Derivatives

f(x)=cos(sqrt(2sinx-e^(x^2-8x)))

g(x)=(ln x)^((ln x)+x)

2. f(x)=sqrt(x)*ln x, if x>0

f(x)=x^2+x+C, if x<=0, What should C be so the function is continous?

3. lim x tends to 0 {5*e^(x/5)-x-5}/{x^2}

4. f(x)=sin x+cos x, What is the equation of the tangent crossing (pi/5, sqrt(2))?

Thanks a lot.