Consider the equation below. (If an answer does not exist, enter D NE.) /(x) = 9 sin(x) + 9 cos(x), 0 2Ï x (a) Find the interval on which fis increasing. (Enter your answer using interval notation.) Find the interval on which f is decreasin g. (Enter (b) Find the local minimum and maximum values of f local minimum value local maximum value (c) Find the inflection points. (x, y) (x, y) = Find the interval on which fis concave up. (Enter your answer using interval notation.) (smaller x-value) (larger x-value) Find the interval on which fis concave down. (Enter your answer using interval notation.)