
Bobosharif S. answered 02/23/18
Tutor
4.4
(32)
PhD in Math, MS's in Calulus
y=tan(x)cos(x) (take log from both sides)
lny=cos(x)ln(tanx) (take derivative form both sides)
y'/y=(cos(x)ln(tan(x)))'=-sin(x)ln(tan(x))+1/sin(x)
y'=y sin(x)(1/sin2(x)-ln(tan(x))