Differentiate the following questions w.r.t. x.
log(cos ex).
Ley y = log(cos ex).
Dofferentiate both sides w.r.t. x, we get
dydx=ddx[log{cos(ex)}]=1cos(ex)ddx{cos(ex)} (Using chian rule)=1cos(ex){−sin(ex)}ddx(ex) (Using chain rule)=−tan(ex).ex=−extan(ex)