Question #d8431

1 Answer
Feb 17, 2017

d/dx sec^3(sqrt(cosx)) = -(3sinxsec^3(sqrt(cosx)) tan (sqrt(cosx)) )/(2sqrt(cosx))

Explanation:

Use the chain rule:

d/dx sec^3(sqrt(cosx)) = d/(du) u^3 * d/(dy) sec y * d/(dt) sqrt(t) d/dx cosx

where:

u= sec(sqrt(cosx))

y= sqrt(cosx)

t = cosx

so:

d/dx sec^3(sqrt(cosx)) = 3u^2 * secy tany * 1/(2sqrt(t)) * (-sinx)

d/dx sec^3(sqrt(cosx)) = 3sec^2(sqrt(cosx)) * sec(sqrt(cosx)) tan (sqrt(cosx)) * 1/(2sqrt(cosx)) * (-sinx)

d/dx sec^3(sqrt(cosx)) = -(3sinxsec^3(sqrt(cosx)) tan (sqrt(cosx)) )/(2sqrt(cosx))