What is the derivative of y=sec^2 x + tan^2 xy=sec2x+tan2x?

2 Answers
Jun 23, 2018

f'(x)=2sec^2(x)tan(x)+2tan(x)*(1+tan^2(x))

Explanation:

Note that

(sec(x))'=sec(x)tan(x)
(tan(x))'=1+tan^2(x)

Jun 23, 2018

Shown below...

Explanation:

Another way of thinking about it:

1 + tan^2 x = sec^2 x

=>1 + tan^2x + tan^2 x = sec^2 x + tan^2 x

=> 1 + 2tan^2 x = sec^2 x + tan^2 x

=> d/dx ( 1 + 2 tan^2 x )

Use d/dx tanx = sec^2 x

Use chain rule:

= 2*2tanx * d/dx tanx

= 4tanx sec^2x