Question

On the interval (0, 21), the highest point on the graph of f(0) = cos O is: O (π, 1)O (2π, 1)

Answer 1

$f(2\pi)=\cos (2\pi)=1$$\begin{gathered} 1\text{ is the biggest value of cos}\theta.\text{ And within the interval (0, 2}\pi),\text{ } \\ \text{cos}\theta=1 \\ at\text{ }\theta=0\text{ or 2}\pi \\ \end{gathered}$

Hence the correct choice is

(2π, 1) ​