Question

Find the derivative of the function f(x) = cos^2(x) + tan^2(x)

Answer 1

I got 2cos(x)sin(x) + sec2(x)

Answer 2

please keep in mind the the first derivative of \(\cos x\) is \(-\sin x\)

Answer 3

namely:
\[\frac{d}{{dx}}{\left( {\cos x} \right)^2} = 2\cos x\left( {\frac{d}{{dx}}\cos x} \right) = - 2\cos x\sin x\]

Answer 4

ok right

Answer 5

:)

Answer 6

I'm confused what do that tell me?

Answer 7

wait now im get 2tan(x)sec^2(x) - 2sin(x)cos(x)