cos(2:z:) 5a 2 ] 2 5111(33) on the interval [71', . Let x) : (a) Find all critical points and classify them. Express the critical points in the form (a, f(a)). Show all your work. (b) Find the global maximum and global minimum of f in the given interval. Justify your answer. (c) Determine all intervals of concavity. Show all your work. (d) Sketch the graph of f(:c) by hand (do not show steps, just a sketch of the nal graph)