How do you differentiate f(x) =[(sin x + tan x)/(sinx* cos x)]^3?

1 Answer

Rewrite this as

f(x) =[(sin x + tan x)/(sinx* cos x)]^3=> f(x)=[(sinx+sinx/cosx)/(sinx*cosx)]=> f(x)=[(1+cosx)/cos^2x]^3

Hence its derivative is

(df)/dx=3*[(1+cosx)/cos^2x]^2*(d[(1+cosx)/cos^2x])/dx

Now we have that

d/dx((1+cos(x))/(cos^2(x))) = (cos(x)+2)*tan(x)*sec^2(x)

Finally

(df)/dx=3*[(1+cosx)/cos^2x]^2*(cos(x)+2)*tan(x)*sec^2(x)