`f(theta) = sec(theta)/(1 + sec(theta))` Differentiate.

kspcr111 | Student

`f(theta) = sec(theta)/(1 + sec(theta))`

so,

`f'(theta) = (sec(theta)/(1 + sec(theta)))'`

 `= (1- (1/(1 + sec(theta))))'`

  `= 0 -(1/(1 + sec(theta)))'`

  `= - tan(theta)* sec(theta)/(1 + sec(theta))^2`

` =- tan(theta)/((1 + sec(theta))^2* cos(theta))`