x=4sin(t) and y=2cos(t). I found the first derivative to be -(1/2)tan(t). How do I find the second derivative?
$\displaystyle \displaystyle \frac{d}{dx} \left(\frac{\frac{dy}{dt}}{\frac{dx}{dt}}\right) = \frac{d}{dt} \left(\frac{\frac{dy}{dx}}{\frac{dx}{dt}}\right)$
$\displaystyle \displaystyle \frac{d}{dt} \left(\frac{-\tan{t}}{8\cos{t}}\right)$
do the quotient rule to finish ...