Find any critical numbers of the function f(Ø)= 2secØ +tanØ, 10π < Ø < 12π

Question

A. 67π/6
B. 71π/6
C. 63π/6
D. A and B

Answer 1

well,

f'(Ø) = 2secØ tanØ + sec^2Ø
= sec^2Ø(2tanØ cosØ + 1)
= sec^2Ø(2sinØ+1)

f'(Ø)=0 when sinØ = -1/2

Now, what else is a critical number?