How do you find the derivative of y = [(tanx - 1) / secx]?

1 Answer
Jan 29, 2017

dy/dx=cosx+sinx

Explanation:

We need to know the following derivatives:

  • d/dx(sinx)=cosx
  • d/dx(cosx)=-sinx

First we can simplify the function using tanx=sinx/cosx and secx=1/cosx:

y=(sinx/cosx-1)/(1/cosx)=cosx(sinx/cosx-1)=sinx-cosx

Then the derivative is:

dy/dx=d/dx(sinx)-d/dx(cosx)

dy/dx=cosx-(-sinx)

dy/dx=cosx+sinx