Find the critical points of the function and use the First Derivative Test to determine whether the critical point is a local minimum or maximum (or neither). (Enter your answers as a comma-separated list. If an answer does not exist, enter DNE.)
f(θ) = 15 sin(θ) + 15 cos(θ) on (0, 2π)
local minimum
local maximum
Determine the intervals on which the function is increasing or decreasing. (Enter your answers using interval notation. Enter EMPTY or ∅ for the empty set.)
Increasing
Decreasing