The correct option is B 2
log y=(tan x)tan xlog (tan x)→(1)Taking log again, we get from(1)log(log y)=tan x log (tan x)+log(log(tan x))Differentiate with respect to x1log y.1ydydx=sec2 x log (Tanx)1TanxSec2x1log(Tanx)1TanxSec2x ∴dydx=y logy sec2 x(log(Tanx)+1+1Tanx log (Tanx)) =y(Tanx)Tanxlog Tan.Sec2x[(log(Tanx)+1)+1Tanx log(Tanx)]=y(Tanx)TanxSec2x[log(Tanx)(log Tanx+1)+Cot x]When at x=π4,y=1∴dydx=1.1.2(0+1)=2