Please solve

Consider the function f(x) = x - 82tan x . Find the critical number(s) of f in the interval [0, 19]. Find the values of a in the interval [0, 19] at which the function attains its absolute maximum and absolute minimum values. Answer: The critical number(s) of f in the interval [0, 19] is x = W The absolute maximum of the function f occurs at x = The absolute mimnimum of the function f occurs at x =