Question

f'(x) =-4sin(x) + 7sec^2(x)
find f'(4pi/3)

Answer 1

Have you considered substituting \(x = 4\pi/3\) into your equation for f'(x)?

Answer 2

yes i already found the prime but i dont know how it would work out since there is sin and cos
@tkhunny

Answer 3

You are given what f'(x) is and you're asked to find f'(4pi/3). So just plug in x = 4pi/3, as @tkhunny suggested, in to f'(x) and evaluate...

@foreveryounging97

Answer 4

\(\sin(4\pi/3) = -\sin(\pi/3) = -\sqrt{3}/2\)?

Answer 5

18/7

Answer 6

\(\sec(4\pi/3) = 1/\cos(4\pi/3) = -1/\cos(\pi/3) = -1/(1/2) = -2\)

Perhaps you should back up a step and brush up on your trigonometry?