Question

Determine the second derivative of y=cosxtanx. Thanks :)

Answer 1

$f(x)=cosxtanx\\\\(cosxtanx)'=\left(cosx\cdot\frac{sinx}{cosx}\right)'=(sinx)'=cosx\\\\(cosx)'=-sinx\\\\f''(x)=-sinx\\\\\frac{\delta^2 f}{\delta x^2}=-sinx$