Find the second derivative f′′(x)f''(x)f′′(x) of f(x)=ln(cos(x))f(x) = \ln(\cos(x))f(x)=ln(cos(x)).
−sec2(x)-\sec^2(x)−sec2(x)
tan2(x)\tan^2(x)tan2(x)
−tan2(x)-\tan^2(x)−tan2(x)
sec2(x)\sec^2(x)sec2(x)